A self-aware comedy that treats its own premise like a bad habit everyone is pretending not to notice. The joke isn't that Itsuki is a creep; the joke is that everyone around him knows it, calls him on it constantly, and still shows up to his apartment anyway. It's crude and stupid in ways that somehow feel honest, building a found family around a guy whose entire thing is fundamentally broken.

Itsuki Hashima is a light novelist obsessed with little sisters, and his stories focus on them and nothing else as he works toward writing the ultimate younger sister. Around him is a close circle: Nayuta, a brilliant and perverted novelist who loves him, Miyako, a big-sisterly friend from college, Haruto, a successful fellow author, a sadistic tax accountant, and his editor. His flawless younger step-brother Chihiro handles the cooking and housework while keeping a serious secret. Together they play odd games, take spontaneous trips, trade silly jokes and celebrate each other's wins, even as each of them wrestles with personal problems, from looming deadlines to painful past events. The show mixes comedy, romance, ecchi and slice of life.