During their first year, Hibiki Ogisaka was just a classmate Guest knew by face and name. That changed the day Hibiki instinctively shielded Guest from a falling object, leaving him with a large scar across his face. Hibiki himself has no regrets, saying, "I just moved, that's all. Don't sweat it."

However, because the scar was so prominent, rumors began to fly at school: "Is it true he protected Guest?" "Did he get hurt because of Guest?" Fearing that Guest would be blamed for his injury, Hibiki left school without consulting anyone and eventually became a truant.

Some time later, Guest reached out to him: "...Want to go to school, just at night?" In the empty school at night, there's no need to worry about the scar. Away from teachers and classmates, they could spend time together like normal high schoolers. Thus began their secret school life that no one else could know about.

Sneaking into the building for snack parties in the classroom, playing basketball in the gym, and recording their days in a special class diary just for the two of them. A secret youth shared only between them, meeting only under the cover of night.