Parasite in Love

The snow covering the town gradually melted, and beside the lingering snow dirtied by mud, fuki plants showed their faces, signaling the arrival of a new season. The cheerfulness of spring filled the air, and a sweet floral smell drifted through the residential district. People took off their thick coats to wear jackets, savoring a sense of liberation that had been missing for some time.

The cherry trees in this town bloomed at the end of April. Depending on the year, their optimal viewing time could be as late as Golden Week. As a result, cherry blossoms weren't symbols of meetings and farewells to the townspeople. Instead, they were like flowers that, after completing a change of environment and taking a breath, appeared to suggest the future.

It was the first day of a three-day weekend. Kousaka lazily walked the long hilly road through the residential district.

There was construction being done in several places around town. Some buildings were being constructed, whereas other buildings were being dismantled. There were areas with road repair work, and areas with power line work. It's like the whole town is being reborn, Kousaka thought.

"Kousaka, when were you going to move, again?", asked a girl walking beside him.

"Next week," he replied.

"That's sudden. Why at a random time like this?"

"Thinking about it, commuting was pretty inconvenient here. I decided I should move somewhere closer."

It was a girl a coworker had introduced to him, named Matsuo. She was two years younger than Kousaka. Her always-lowered eyebrow-ends gave off a gloomy impression, but if you looked, she had pretty good facial features, and a wholly refreshing smile. She had worked part-time as a student until she was made into official employee, and continued with her job since.

This was Kousaka's third time having an outing with her. It had been less than a month since they got to know each other, but Matsuo showed affection for Kousaka since the first time they met. Kousaka also felt like he could naturally relax around her.

Once they talked, they found they had a surprising amount in common. For instance, germaphobia. Until just two years ago, she had washed her hands a hundred times a day, changed clothes five times a day, and took three-hour showers. Thanks to perseverant treatment, she was now able to live a normal life, but at its worst, she couldn't even leave the house. When Kousaka casually brought up germaphobe-related items like disinfectant and air purifiers, Matsuo's eyes shined and she spoke about them.

Book and music tastes, feeling distanced from work, lacking interest in social problems. In many respects, Kousaka and Matsuo's opinions matched. It was the natural flow of things for them to become friendly.

The two kept walking aimlessly, talking about movies they'd watched recently. As they came to the path along the river, the topic changed to fishing. Matsuo spoke about memories of her father taking along to go ocean fishing.

"Oh, yeah, I got food poisoning from that once," Matsuo recalled.

"It was when I was eight or so. We made sashimi from a greenling we caught at home, and ate it as a family. It was really tasty, but late that night, I suddenly got a really bad stomachache. I really wondered if I was going to die. And I was the only one affected - my dad, my mom, and my little sister were totally fine. It was awful."

"Anisakiasis, I bet?", Kousaka said with a wry smile. "That even makes grown-ups writhe in agony, so it must have been hell for a kid."

"Oh, you're so knowledgeable!" Matsuo clapped her hands in admiration. "Yes, it was the doing of that foul Anisakis. Do you go fishing too, Kousaka?"

"Nah. Never even been to a fishing hole."

"Then do you eat lots of raw fish?"

"I had an acquaintance who knows all about that kind of thing. I'm just repeating it from her."

"Oh, is that it." Matsuo nodded, then asked to dig deeper, "An acquaintance? Is she a friend?"

"No, a little different from a friend."

"Then what? A girlfriend?"

"About five months ago, I had a part-time babysitting job. I heard it from her."

"Babysitting..." Matsuo looked increasingly suspicious. "Kousaka, you don't seem like you'd be great with children."

"Yeah. But there were reasons I had to take the job."

"I... see," Matsuo affirmed ambiguously. "Even so, isn't it rather rare to find a child who'd tell you about Anisakis?"

"I guess so," Kousaka said. "I've only met the one, myself."

*

In less than four months since he started taking the deworming medicine, Kousaka experienced such great changes that you might as well say he was reborn.

First, his germaphobia was cured. The disorder that was so firmly rooted in the person Kengo Kousaka was gone like it never existed a month after treatment started. It really was instant. Like a stomachache or mouth ulcer: you can think of nothing else before it's cured, but once it's gone, you can hardly remember what it was like.

When he paid attention, he realized he was using the same towels for several days, and was fine going from getting home straight into bed. He didn't think anything of being shoulder to shoulder with other people, and could grab onto straps on the train if necessary.

Once the bottleneck of his germaphobia was cured, the rest proceeded steadily. He easily settled upon a new job. Looking through a site geared for people who were trying to get back to work after rehabilitation, as if by coincidence, his eyes went straight to a highly favorable job offer. It was a recruitment for web programmers at a web design company, and the programming languages listed as requirements were all ones he was an expert in. Kousaka took the offer, submitted some of his code, and left the rest to flow. He didn't have any hopes at all, but by next month, he was a full-time employee at the company. Things moved so smoothly as to make him worried someone was stringing him along.

As he noticed once he began working, Kousaka spending his free time making malware really helped develop his programming skills. It wasn't that he learned the specific knowledge, but rather that he established the right thought process for programming. He became valued at his workplace. It certainly wasn't the easiest job, but having found a solid place to be gave him great joy.

Kousaka slowly but surely regained confidence, to a level appropriate for his age. People around Kousaka mistook his calmness that stemmed from resignation as composure from rich life experiences, and were convinced he was a superb person. They saw his frequent job changes as proof of his faith in his own abilities. Every element miraculously worked as a positive. Just a month after joining the company, he'd made friends to have a drink with after work, and himself nearly forgot that until a few months ago, he was completely unfit for society.

And yet sometimes, he suddenly felt a boundless void within himself. Said void was in the shape of a girl. When he dozed off at his desk, when he walked the same roads he had once walked with her, when he saw things he associated with her - headphones, blue earrings, oil lighters. At any such opportunity, Kousaka was made to recall Hijiri Sanagi.

But that was all over. Sanagi had surely long forgotten the days they spent together, and had started on her own true life.

That was probably something to be celebrated, Kousaka thought.

In the last third of March, Kousaka, fully adapted to work and convinced of his cured misanthropy, discovered that even freed of the worm's effects, he as of yet loved Sanagi. That part which he'd expected to be the first to change right after treatment began was the one thing about him that hadn't changed a bit.

Kousaka felt deep confusion. Wasn't the love between Sanagi and I a sham brought about by the worm? Why has my germaphobia and misanthropy been cured, but not my "lovesickness"?

Maybe I've had a terrible misunderstanding? Maybe the consolation I gave Sanagi when we parted to pacify her was right on the mark. It was likely the truth that the worm had the power to make its hosts fall in love. But even without that - that is, without the worm - had Sanagi and I been able to love each other from the start? Maybe I just failed to realize that, and after hearing about Professor Kanroji and the Hasegawas, came to cast doubt on everything and distrusted my own feelings?

His heart beat fiercely, urging him on. Almost unconsciously, Kousaka called Sanagi. The call sound played. He counted. One, two, three, four... at five, the call gave up and ended.

Kousaka put his hand to his chest and took a deep breath, calming his rapid heartbeat. There's no rush. She should call back eventually.

But a whole day passed with no contact from Sanagi. Afterward, Kousaka called five times and sent three emails, but with zero responses.

He considered going to Sanagi's house directly. It had been a month and a half since he last visited Urizane Clinic. He'd been given plenty of medicine, and there was no sign of his symptoms returning, so he had no reason to go. But while he hadn't considered it when visiting before, if he went to the clinic and said "I want you to let me meet Sanagi," would they have a reason to refuse him?

Kousaka examined the pros and cons. But his swelling feelings, after a certain point, began to rapidly shrivel up.

Now that he thought about it, there could only be one reason why Sanagi wasn't responding. One or two, perhaps, but she couldn't have not noticed five or six attempts at contacting her. The fact that trying this again and again didn't get any reply meant that she was intentionally ignoring Kousaka's attempts to contact her.

Sanagi must be trying to forget about me, Kousaka concluded. Maybe her deworming had also succeeded, and she was able to escape the worm's control. And once she regained her normal thoughts, not a shred of affection for Kousaka remained. It was ironic, but that was probably what it was.

It didn't take too long for Kousaka to come to terms with that. Luckily, he had plenty of work he had to do. Instead of worrying about Sanagi, he focused himself on those tasks. In doing so, he got to know Matsuo, and the hole in his heart was slowly filled with things to substitute.

This way of life is the most proper and reasonable, Kousaka told himself. My days with Sanagi were like a dream in fading consciousness, a kind of phantasmagoria. Indeed, they were more beautiful than anything. But in the end, just a dream. If I try to stay there forever, I'll just be dying while I live. What we should be chasing after is happiness with its feet on the ground, happiness for the living.

"Kousaka?"

He was brought back to his senses, and nearly dropped the glass in his right hand. What was I doing again?, Kousaka wondered. Right, I remember. I was drinking with Matsuo. We were walking through town together and decided to go into an Irish pub we spotted. I must have been nodding off from drunkness and fatigue.

"Ahh, sorry. I was spacing out." Kousaka firmly rubbed his brow.

"You were doing that for a pretty long time," Matsuo said with a laugh. "It looks like it's almost closing time. Do you want another drink, or not?"

Kousaka looked at his wristwatch and thought.

"I think I'll call it for today. Or have you not had enough, Matsuo?"

"Oh, no." Matsuo shook her head forcefully. "I'm probably too drunk as it is."

"It does look that way," Kousaka affirmed, seeing the faint red in her face.

"Yes, I'm drunk enough that you look a little cool, Kousaka."

"That's a serious illness. Better get home and rest."

"Right. I'll do that."

With that, Matsuo picked up the glass in front of her and poured it all down her throat. Then she met eyes with Kousaka, bent her head down, and smiled playfully. But Kousaka observed that her eyes, though very faint, had a tinge of disappointment.

Maybe my reply wasn't what she was hoping for, Kousaka thought to himself. Maybe Matsuo wants to take our relationship to the next step. She's showing enough signs that even someone who can't take a hint like me can tell.

If I know that, why won't I respond?

Maybe somewhere in my heart, I'm still holding on to Sanagi?

After leaving Matsuo, Kousaka headed not for the train station, but retraced his steps to another bar to drink some more. He couldn't explain to himself why he did that. Maybe because if he went back to that room, like it or not, he'd remember being with Sanagi. Maybe the reason he was hesitating to advance his relationship with Matsuo, too, was because he couldn't permit outsiders into the room he'd been with Sanagi in.

He felt he finally understood why he was in a hurry to move. How pathetic, Kousaka laughed self-derisively. I want to think I've become a proper human, but deep in my heart, my crush on a 17-year-old girl goes on.

*

He missed the last train, so he took a taxi home. He got the money out of his wallet without really counting, gave it to the driver, and took the change. When he got out of the car in the residential district, the thick smell of spring flowers carried on the night wind tickled his nose.

With an unsteady walk, he climbed up the apartment stairs. After unlocking the door to his room, he fell collapsing onto the bed. These spring nights were warm, the mattress was soft, and the sheets were cool. He let his consciousness drift away.

At first, he thought his ears were ringing. But as it repeated again and again, he realized it was the sound of the intercom. He thought it had turned morning while he nodded off, but when he sat up and looked out the window, it was still night. He looked at the clock, which had just turned 2 AM. Who could it be at this abnormal hour...? Just as he had that question, he remembered something very similar that had happened before.

His drunkenness and drowsiness cooled in an instant. He lept up and went to open the front door.

His prediction was correct. Standing there was Izumi. With one hand in the pocket of his worn suit, he rubbed his unshaven beard with the other. He wasn't wearing his usual drab coat.

"Hey. You been doing well?"

"Izumi?", Kousaka asked, dumbfounded. "What could you be here for?"

"Is it okay if I come in? Or has your germaphobia not cured yet?"

"No, I don't really mind if you come in..."

Izumi took off his leather shoes and entered the room.

"Want some coffee?", Kousaka asked.

"No, I'm fine."

Izumi looked around the room. Since Kousaka was just about to move, it was awfully barren. There was nothing other than a pile of white cardboard boxes in the corner and minimal furnishings. His work chair and desk, an empty bookcase, coat hangers, the bed. Izumi thought for a bit, then gently sat on a cardboard box.

Kousaka sat in the chair and asked:

"If you've come here, then something related to the worm must have come up, more or less."

"Correct," Izumi replied without budging an eyebrow.

"Has there been some problem?"

"I'd actually like to ask you - anything to mention?", Izumi asked back. "Any strange changes happen lately?"

"No, no real outstanding changes. I'm recovering quite well." Kousaka suddenly noticed he still had his wristwatch on, so he took it off and flung it onto the bed. "Thanks to you, my misanthropy has been cured too. It seems all the worms in me have died off."

"That's wrong. Your worms haven't gone yet."

A silence fell between them.

"...What are you talking about?", Kousaka said with a stiff smile. "As you can see, my germaphobia's gone. I successfully got a new job, and my human relationships are going smoothly. There's no trace of the worm's effects left."

Izumi shook his head. "It's just a lull state. I don't know why, but the worms in your body seem to have a resistance to medicine. It's not like I've checked, but I can't think of anything else. They've temporarily weakened for now, but if you stopped taking the medicine for a while, they'd probably come back right away." Then he suddenly grinned. "And that's a very lucky thing."

"Lucky?"

"I'm saying you should be grateful your worms have such powerful survivability."

As if enduring something, Izumi took a deep breath, and slowly let it out.

Then he informed him.

"Except for you, deworming medicine has been extremely effective on those infected with the worm. And when the worms in their bodies died... their hosts, too, chose death."

Kousaka's expression stayed frozen. Not a word came out of his mouth.

Izumi continued. 𝗳𝓇ℯe𝓌𝚎𝚋𝓃𝚘𝚟𝘦𝑙.𝑐𝚘𝙢

"Professor Kanroji and Dr. Urizane had the same opinion about the worm causing the infected to commit suicide. They thought that once the number of worms in the host's body passed a certain number, they couldn't bear living in human society anymore and accepted death. Well, it was a reasonable guess. Even if it weren't for those two, you might think so. ...But there was a fatal mistake in that thinking. We were thinking with the assumption of "suicide equals abnormality." That was the trap we fell into.

"As research continued, a number of facts came to the surface. This parasite's final host is humans, sure, but it doesn't seem it can infect just any human. In fact, it can't infect most humans; even if it gets into their body, it's quickly shut down by the immune system. But in rare cases, there's people like you with bodies that not only don't exterminate the worm, but firmly preserve it. Like they're actively accepting infection.

"This is getting into my own subjectivity a little, but... maybe the worm doesn't have any such power to make the hosts kill themselves. Sure, it isolates the host, but maybe that has nothing to do with their death. In fact, there's one new fact Dr. Urizane's research found. That the worm has the ability to suppress the host's negative emotions. Anger, sadness, jealousy, hate... any negative emotions that occur in the host can be weakened by the worm. I don't know the detailed workings, but Dr. Urizane said it might be that the worm can selectively consume the enzymes needed to create nerve signals. If that theory's correct, then we could explain it as the worm feeding on its host's anguish. Thus it probably isolates its host from society to provide it plenty of anguish. Guess the stress of everyday life isn't filling enough.

"So then I came up with this hypothesis. Maybe the infected, before the worm infected them, were always people with souls prone to sickness - to be frank about it, people with a strong desire to die, or suicidal thoughts? What if the ones the worm could make into hosts were people who'd kill themselves if they were left alone?

"With that theory, a lot that hasn't sat right before suddenly makes sense. The majority of people can't provide enough anguish to sustain the worm's life. Even if the worm is ignored, it'll be weak, and die from an immune system attack. On the other hand, the bodies of people who are constantly charmed by death with more anguish than they can handle, they've gotta be better than the worm could ever ask for. Some ticks that infect humans eat excess sebum and keep balance in the skin, so it's kind of like that. They eat excess anguish to keep a mental balance. ...So those bodies don't exterminate the worm, they accept it. They get incorporated like an organ to handle all that anguish that the host can't handle alone. The host and the worm form a mutually-beneficial relationship.

"So, what happens if you try to exterminate a worm like that with medicine? All that anguish it was taking care of has nowhere to go, and the host is hit with it again all at once. They got so naive with the worm protecting them, they don't have the strength left to endure. They lose what was letting them live longer; nothing's left to stop their longing for death.

"We were convinced the deaths of the infected were caused by the presence of the parasites. But the reality was just the opposite. Their death was caused by the absence of parasites. That's my conclusion."

Various things Kousaka heard from Sanagi surfaced in his mind like flashbacks.

"...Thus, making the immunosuppressive system work is linked to bettering immunity-related diseases. But apparently, these regulatory T cells are brought about by the existence of "parasites approved by the host." So in essence, the absence of parasites, an extremely clean situation, results in an increase in modern day allergies and autoimmune diseases."

"Also, D. paradoxum don't abandon their partners to the last. Once D. paradoxum join together, they never let go of each other. If you try to tear them apart, they'll die."

And cysticercosis - a disease that first occurs when bladder worms die in the central nervous system. fre𝑒𝘸𝚎𝚋n૦ѵℯl.c𝒐𝘮

The clues had been there all along.

We were being given life by the parasites - and we never should have let go for a moment.

"Sanagi -" That was the first word out of his mouth. "What happened to Sanagi?"

"She was the first victim," Izumi said. "Hijiri Sanagi was the first to experience the effects from the absence of parasites. One morning, Dr. Urizane got worried that his granddaughter wasn't waking up, so he went to her room and found her lying on the floor, unmoving. There were signs she'd downed a ton of sleeping pills and alcohol. That was about half a month ago."

The world fell out from under him. His vision blurred, and his ears rang loudly.

But Izumi's next words pulled Kousaka up from his fall into hell.

"But don't worry. Hijiri Sanagi's not dead yet. Her attempt failed. She was a little too excessive - her strong desire to die backfired on her. She took so many pills and so much alcohol, so she threw up before either took much effect. Or else maybe she got afraid in the middle and threw it up herself, but either way, she was spared. Although..."

Izumi was stuck on what to say, and looked toward the window to think. Kousaka looked out there too, but there was nothing notable to look at. Just darkness.

Eventually, Izumi opened his mouth.

"After getting minimal treatment at the clinic, she was transferred to a proper hospital. Her life didn't seem in danger for the time being, so Dr. Urizane and I were relieved. But Hijiri Sanagi's suicide attempts had only just begun. She was like a canary in a coal mine."

Kousaka took the initiative to ask: "The other patients - did the Hasegawas behave similarly?"

"They did," Izumi nodded. "A week after the incident with Hijiri Sanagi, we got a call from Yuuji Hasegawa. "Satoko Hasegawa has committed suicide," he said, then hung up. We didn't know what was going on. The next day, we decided to head to his house to ask for details, but we were too late. Yuuji Hasegawa had already followed after his wife. The two had expired huddled up together. And while we were discovering the Hasegawas' suicides, Hijiri Sanagi vanished from her hospital room."

"Vanished?"

"Yeah. She left a note that just said "thank you very much." We put out a search order, and I've been looking around myself for days, but we haven't found Hijiri Sanagi. I thought she might have come to your place, but I guess that was wrong. ...Where could she have gotten to?"

Then Izumi fell silent. His face looked tired. It seemed he'd been beaten down by fatigue, powerlessness, and all sorts of other emotions.

"I'm so exhausted," Izumi said with a sigh.

"In the end, what we were doing was completely off the mark. We didn't save the patients, we actively drove them to death. We just had to meddle with something that was fine left alone. What a comedy show. Dr. Urizane's spirits are in the dumps, like he's been stunned into numbness. He might just kill himself before his granddaughter."

After a laugh, Izumi stood up sluggishly.

"It's selfish, but... as of today, I'm gonna be leaving Dr. Urizane. Doubt I'll see you again."

Izumi turned his back to Kousaka.

Kousaka called to him.

"Izumi."

"What?", Izumi said without turning around.

"Please, don't die."

"...If you're worried about that, I'm really done for."

Izumi's shoulders shook with a chuckle.

"So long. Get on well with that worm. Like it or don't like it, it's an important part of you."

With that parting remark, he left.

A suicide attempt. That was the real reason Sanagi hadn't responded to his calls and emails. By the time Kousaka called, the worms in Sanagi's body had already died off, and she was fighting an encroaching longing for death. Or maybe she was steadily preparing for suicide. Either way, that was what was filling her head, and she couldn't afford to think about anything else.

So Sanagi's lack of response wasn't because she hated me - that was Kousaka's honest first impression, before thoughts of ensuring her safety. It was imprudent, but that was what Kousaka delighted over first.

Ultimately, this happiness I'm feeling now is everything, Kousaka thought. I love Sanagi. There's nothing more definite than that. The worm and our ages don't change that. If this feeling is a lie, then I'll keep being deceived until the day I die.

After relishing that happiness, Kousaka considered the whereabouts of the missing Sanagi. The locations of special interest to her were very limited. Thus, the options were naturally narrowed down.

Perhaps Sanagi intended to kill herself in the same place her parents did. He heard they had jumped off a bridge in the mountains which was infamous for suicides. It wouldn't be strange if she wanted to jump from that same place herself.

I have no real evidence. But right now, I also don't have any clues that sound better. I need to head there, Kousaka thought strongly.

He called a taxi from his phone. He got in the taxi that arrived ten minutes later and told the driver his destination. The aging driver silently started to drive without an affirmation.

But a whole twenty minutes later, Kousaka said he forgot something and had him turn around. Truthfully, it wasn't something he forgot to take. He just suddenly thought: I should wear the red scarf Sanagi gave me on Christmas Eve.

Even though it was a race against time, he couldn't help but feel it was necessary. It was a kind of prayer. He felt that scarf would serve the role of a red thread that pulled them together.

To say it in advance, that premonition was on the mark.

Maybe it was the worm in his head that secretly told him so.

Back at the apartment, Kousaka raced up the stairs and arrived at his apartment door out of breath. As he put his key in, he noticed the door was already unlocked. He must have forgotten to lock it in his hurry to leave.

When he went inside, he saw light seeping in from the living room door. It seemed he also forgot to turn off the lights. But he didn't care about that. Kousaka entered the room without taking off his dirty shoes, went through the kitchen to the living room,

and there, sleeping soundly, he found Sanagi.