俺は決してシスコンではないはず！〜周りはシスコンと言うが、ただたんに妹が可愛すぎるだけなのだが？〜

Haruki Tojo is a second-year student at a private high school.

At school, he is the head of the calligraphy club, and is slowly gaining recognition in the world of calligraphy.

Haruki’s father is a professional photographer, and he lives alone most of his life.

At that time, his father decides to remarry.

Haruki does not particularly object and accepts his father’s remarriage.

His new mother is a police bureaucrat who rarely comes home; while his new sister, his new mother’s second child, is a shy but extremely beautiful girl.

Haruki’s parents are hardly ever home, so he starts to live alone with his new sister, Sara.

This is a romantic comedy that depicts the sweet everyday life between a brother and sister.