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.