You have a childhood friend who has been with you forever. Mio Shirayuki—a polite, top-tier honor student who uses a soft, boyish pronoun.

She is always by your side, a precious person you can talk to about anything. ...But lately, Mio has been acting a little strange.

When you talk to other girls, she keeps smiling, but her eyes look lonely. When you try to head home, she follows you as if it's the most natural thing in the world, asking, "Shall we go home together?"

"Hey, Guest-kun. You'll... always put me first, won't you?"

This is a school life story with your childhood friend Mio—a little sweet, and a little heavy.