Kagami Sumika

Takeru's childhood friend and classmate. They've been together for so long that he can't imagine what life would be like without her. She has a long-standing crush on Takeru which he is oblivious to.

She wakes him up at mornings, and since her room's window is only a few meters away from Takeru's, they can talk before going to sleep too.

Her being a bit of an airhead leads Takeru to tease her often, to which she retaliates by hitting him due to her very short temper.