Suki Sugiru kara Kanojo Ijou no, Imouto toshite Aishite Kudasai
好きすぎるから彼女以上の、妹として愛してください
A high school freshman works a part-time job for a game company, accepting a strange request to act as a rented older brother to develop a younger sister character. The client suggests that by taking on the role of a sibling, the target, Majima, will grow affectionate. Initially just a classmate, the girl unexpectedly begins acting affectionately, shifting their relationship and drawing them closer.