Tomodachi no Imouto ga Ore ni Dake Uzai

There’s no collusion, and there’s no girlfriend needed. Value can only be found in the creatures called ‘friends.’

‘Adolescence’ in itself is inefficiency, and in order to live through the harsh race called ‘life’, useless things should be tossed aside—

Or so I, Ooboshi Akiteru, believe, as I find an intruder in my own room.

Kohinata Iroha. She is neither my little sister nor my friend, and never in a million years could she be considered my girlfriend. She’s just a friend’s little sister. And this quite frankly annoying and extremely bothersome Kouhai actually has another secret. To be precise, she is the mystery member of the mobile game production company “5th Floor Alliance.”

The “5th Floor Alliance” consists of myself as producer, the genius programmer OZ (as in Kohinata Ozuma), the illustrator Murasaki Shibikibu-sensei (real name Kageishi Sumire), and finally, the rising star of the light novel industry and the best-selling author who helps us for unknown reasons in his duties as a scenario writer, Makigai Namako. The four of us make up the core of the “5th Floor Alliance.”

Our masterpiece “The Screaming Night of Dark Koyama” is a horror game with charming characters. Thanks to its contents, it garnered great popularity in the market, since there hasn’t been a game like this before, and a great number of players found it to be very enjoyable.

The person who lent all the various characters their voices was none other than Kohinata Iroha. Using only her voice, she is able to represent both young and old, male and female, with perfect acting. I’ve deemed her as “the owner of the rainbow-colored voice.” However, due to certain circumstances, she hadn’t been able to use her absurd talent, which is why I gave her an opportunity and the support she needed.

I’m not looking for a reward. It’s just that wasting such great talent would be a great loss to society. I hate useless waste and inefficiency more than anything, and this is how I acted according to this belief.

And even though I didn’t do it to curry favours, Iroha has been constantly coming and going from my apartment, annoying me at every chance. She barges into my home, enjoys herself when I get flustered by her extremely well-formed body, and teases me every chance she gets. Even so, she acts completely normal around everyone other than me, and she’s even a well-known honour student at school… What a troublemaker.

But while we were spending those nonchalant days in peace, the black ship1 arrived.

The transfer student—Tsukinomori Mashiro.

She’s the daughter of my uncle. My uncle is the representative and company president of the very lucrative Honey Play Works company: Tsukinomori Makoto. To keep it simple, Mashiro is my cousin, and she wanted to step outside of her comfort zone as a shut-in, so she transferred to my school.

In order to enable her return to society, we pulled out all the stops in order to get her into the “5th Floor Alliance,” and although there were some twists and turns, it had become a very important step towards her rehabilitation. The unintended side effect, however—

‘Mashiro loves you. More than anything in the world.’ 𝑓𝑟eℯ𝒘𝗲𝑏n𝑜𝚟𝙚𝒍.𝒄o𝐦

Her explosive confession threw the “5th Floor Alliance” into complete disorder.

1 “Black ship” refers to the American black ships that arrived at the Japanese coast during Japan’s seclusion in the 19th century. They forced the country’s borders wide open and brought great change overall.