Ichika went to Kamakura Girl High School with her friends, Satsuki who had a sturdy mind, Keiko who was a gentle girl, and Michiru who has something mysterious about her. On the last day of the first term, after home room, she lost her valued item while she was cleaning the room. On her way home, she remembered where she left it. So she came back to the school at night to get it.
Then, she met a cheerful and entergetic girl, Manatsu. The summer for the two girls began.