Mitsuki Kimura appears in a specific story segment. She has dated Tooru Tanaka for about six months, yet constantly wonders if he feels the same depth of emotion she does. This uncertainty shapes her interactions, especially during romantic moments or expressions of affection.

Seeing others navigate romance easily highlights her own struggles. She finds initiating simple physical contact, like holding hands, intensely embarrassing, sometimes wishing to vanish. Tooru's passive nature, reacting rather than initiating, leaves her without clear signs of his affection and deepens her confusion.

Seeking insight into Tooru's perspective, Mitsuki impulsively puts on his glasses, triggering unforeseen events and revealing her spontaneous streak when seeking emotional clarity. Outside romantic situations, she is generally lively and energetic, though displaying a certain naivety for her age. Her shyness and vulnerability emerge strongly in romance, where she becomes easily flustered or embarrassed.

A distinctive habit is her tendency to close one eye during awkward or self-perceived embarrassing moments, physically manifesting her discomfort.