Recently, high school student Aya Osawa has taken an interest in someone. This person works as a clerk at a CD shop and has a cool demeanor, dressed in black attire. Aya admires this mysterious figure, yet the person she's drawn to is actually Mitsuki Koga, a classmate sitting beside her at school, and not a male but a female.

Aya seems to be lost in her own world, rambling with Chizuru and Mao about "Onii-san", not noticing the nervous and uncomfortable expression from Mitsuki, she continues to talk