Mana Natsukawa is a supporting character in Oreshura and the younger sister of the main female lead, Masuzu Natsukawa. She is a middle school student who attends a private girls' institution and is often seen accompanied by a personal bodyguard. Mana has blonde hair styled in twin tails and blue eyes. Her primary motivation throughout the story is to have her older sister, Masuzu, return to Sweden to live with their father. To that end, she keeps a close watch on Masuzu’s activities and regularly reports them back to their father. Despite her persistent efforts to interfere, Mana is not portrayed as a villain; she possesses a sharp tongue and can be blunt, but she genuinely cares for Masuzu and wants what she believes is best for their family. Her relationship with her sister is complex—frequently marked by irritation and conflict, yet underpinned by a deep familial bond. Mana also takes an interest in Eita Kidō, mainly because he is Masuzu’s fake boyfriend, and she occasionally interacts with him in an attempt to influence the situation. Her role in the narrative is that of a catalyst who introduces external pressure on the fake relationship and adds another layer of complication to the romantic misunderstandings. Over the course of the story, Mana’s interactions with Masuzu and Eita gradually reveal a more vulnerable side to her personality, though her determination to reunite her family remains a constant. She does not possess any supernatural or extraordinary abilities, relying instead on her cleverness and the authority granted by her father to pursue her goals.