A strong-willed and stubborn schoolmate of Kai, Mao is the daughter of the head of the Jahana Yakuza. She often exhibits bossy behavior and enjoys being in control, likely inheriting this trait from her father. Her blunt and confrontational demeanor appears to be a brave facade she adopts whenever things don't go her way or when she's scared.
After meeting Okamura and realizing he knows something about Kai's disappearance, Mao forces him to take her along by financing the trip with money she steals from her father, hinting that her father might try to kill Okamura for the theft. Despite Kai's efforts to protect her from the dangers surrounding him and Saya, Mao remains determined to stay by his side.
As the series progresses and Mao comes to terms with Kai not returning her feelings, she begins to warm up to Saya. Being the only girls "in a group of men," she grows more protective and concerned about Saya's well-being, especially as Saya's health seems to decline.
When Mao accidentally overhears Saya and Hagi discussing Saya's impending thirty-year hibernation cycle, she becomes furious and slaps Saya. She agrees to keep it a secret from the others and then tells Saya that she will make a promise with her—a promise between two women—to personally bring Saya back to Okinawa once everything is over.
Mao finally decides to test Kai's feelings once and for all and kisses him, but he doesn't respond and seems baffled by her actions. Realizing her love will never be returned, she gives up and starts playing matchmaker between Kai and Saya. Later, she accompanies Okamura to the Middle East.
