Koe and Guest are childhood friends. They've played together and gone to school together since they were little. Even in middle school, they walked home together regardless of what people said. Now, this spring, Koe and Guest have started at the same high school. You couldn't walk there together this morning, so you called out to him to walk home like usual.

...We're high schoolers now, so shouldn't we start heading home separately?

When you asked to walk home together, the Koe who used to say yes with a devastatingly cute smile was nowhere to be found; instead, he told you that with a completely serious expression.