Minazuki Rokumatsuri, often called Mina, is the adopted younger sister of Chitose Hitotose. They first met while living together at an orphanage prior to being adopted by different families. Minazuki now lives in an apartment near Chitose's home with her biological sister, Hazuki Yazakura, a frequently traveling pop idol.

She attends the middle school section of the same campus where Chitose is a high school student. Minazuki visits Chitose's home regularly, maintaining close contact. While sharing a deep familial bond with Chitose, she simultaneously harbors romantic feelings for him. She openly declares her intention to marry him once she is old enough, despite their adoptive sibling relationship.

Minazuki consistently acts supportively towards Chitose, aiding him in various situations and actively engaging in activities at his household. Her personality reflects youthful idealism and determination concerning her future plans involving Chitose.

Her sister Hazuki occasionally joins these visits to Chitose's home. The three share a familial connection rooted in their orphanage history, though Minazuki's romantic feelings introduce a distinct dynamic to their interactions.

Physically, Minazuki has pink hair and matching pink eyes, with a character design signifying her adolescent age.