Occupation Novelist Itsuki is the protagonist of the series who has an obsession towards younger sisters. He is a novelist who debuted when he was in high school; all of his novels feature younger sisters as the heroine. In the span of five years, he has published 20 books, some of which have ranked in the top 10 weekly rankings for light novels on Oricon. Despite his success, his irrational personality and writing style has led to mediocre success compared to his fellow writers.

Spoiler

He admits to having feelings for Nayuta Kani, but he won't go out with her until he becomes her equal instead of living in her shadow.

Spoiler

His relationship with his father became worse when his father remarried to Chihiro's mother only 3 years after Itsuki's mother died.