The day I met my step-brother, I realized, "This is a game world, isn't it?" My step-brother, Christophe, was a character destined to become a serial killer due to his warped affections. "Wait, he's only three, isn't he? If I raise him myself now, can I still make a difference...?" This is the story of an older sister who strives to keep her step-brother from becoming a serial killer.

※Occasional extra chapters

Published as a book by Arianrose, it has a completed comic adaptation and a song adaptation.