The secret of Koiko, the student council secretary attending an elite girls' school. It is that she writes down her "yuri fantasies" about her admired student council president in a notebook. She never intended to show it to anyone, but of all people, it was discovered by the president's younger sister, Nika, leading to days of teasing over the notebook... A high-tension gag yuri comedy begins, where fantasies and reality intersect♡.