Tachibana Junichi is a boy from class 2-A. One day walking home, he saw by accident a girl's "underwear." Afterward, he finds outs what it really was... The first arc focuses on Tachibana Junichi relationship with Ai Nanasaki. The second arc on Morishima Haruka. The third arc on Sakurai Rihoko.

The series is based on the Amagami love simulation game.