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.
Sōra is a high school student who is basically invisible at school. He is friends with Chūya, who is an unpredictable character that often surprises those around him. Sōra and Chūya both have feelings for the same classmate, Kio Machida. The Machida girl refuses to come to class, because she doesn't want to dye her naturally brown hair black. Their school has unreasonable school rules, especially about uniforms, which include requiring all students to have black hair. Sōra and Chūya decide to stand up to change their school's black school rules so that Machida won’t have to repeat a year of school from missing too many classes.