Ishimori Uka is very shy and has a hard time making friends. When she was a middle school student, students made fun of her by calling her "stone". Around that time, she met Miura Kai with lemon color hair. Because of him, she entered the same high school. Uka now wants to overcome her shyness and have friends. Kai is a popular student at the school, but he doesn't talk much or seem interested in others. He doesn't know why, but he becomes concerned with Uka. Uka has admired Kai, and she now has feelings for him. Kai has a secret, which no one knows.

Akira Tachibana is a soft-spoken high school student who used to be a part of the track and field club. Working part-time at a restaurant, she finds herself inexplicably falling in love with her manager, a divorced 45-year-old man.

The director, twenty-three-year-old Iwabuchi Hiroki, is a permanent part-timer who on weekdays does menial work at a factory for 1,250 yen an hour, and on weekends takes on casual temporary work in Tokyo, a city he is fascinated with. He joins a demonstration demanding rights for permanent part-timers, and is featured on TV as "a poor, unhappy temporary worker." Despite having made his own choice to live as a permanent part-timer, he says that "the days feel like drowning in shallow water." But during the diary-like documentation of his life, something changes...