My Friend's Little Sister Has It In for Me!

友達の妹が俺にだけウザい

Akiteru Ooboshi looks like an unremarkable student, but he quietly runs a game-development group called the 5th Floor Alliance with his best friend Ozuma Kohinata. His uncle agrees to bankroll the project on one condition: Akiteru has to pose as the boyfriend of his cousin Mashiro Tsukinomori. Ozuma's little sister Iroha, a model honor student at school who saves her relentless teasing for Akiteru alone, has strong opinions about that arrangement. This light novel is the original source behind the Tomodachi no Imouto manga.