In middle school, Uka Ishimori was nicknamed “Stone.”

In order to change herself, she enrolled in Hachimitsu High School, known for its culture of student liberty. Seated in at the desk next to her in the same class is Kai Miura, a coolly freewheeling boy with lemon-colored hair. In truth, Uka met Kai once in middle school, and decided to attend Hachimitsu based on a single word he said to her. To Uka, the popular Kai is a distant presence.

Yet somehow, Kai starts to look after Uka. With Kai encouraging her, Uka gradually begins to fit in with her classmates…

But... Uka’s world is gradually changing with Kai’s presence. —

Now, I am in the center of the endlessly spreading light.