In the morning, a crowd has formed in the hallway in front of the classroom. There's only one reason. Kanzaki Mizuki has arrived at school. "Good morning, Kanzaki-san!" "I saw your stream yesterday!" "Can I shake your hand?" Surrounded by those voices, she returns a smile to each and every person. She's perfect, I think. At least, everyone here thinks so. It doesn't change even after she enters the classroom. When she takes her seat, people naturally gather around her, and she's always the center of attention. Her idol debut is coming up soon. Everyone is convinced it's only natural.

――Except for one person. The seat by the window at the very back of the classroom. The boy sitting there doesn't look toward the commotion. Even though they're in the same class, he doesn't exchange words with her. ――At school, that's the extent of their relationship.

After school. Their houses are next door to each other, and the windows of their second-floor rooms face one another. If they open their windows, they're close enough to have a conversation just like that. It's been the same since they were kids. When one of them opens their window, it's a signal. She slides her window open with a clatter.