Ayumu's first friend at Nishidate High School, she quickly became an ex-friend after her boyfriend, Sako Katsumi, spread lies about Ayumu. Manami also exhibited predatory behavior towards Miki Hatori. Obsessed with her boyfriend, she even became suicidal when they broke up, although the separation turned out to be temporary. Manami was once bullied in middle school because she caught Katsumi's eye; those he rejected became jealous and took out their frustrations on her.
Coming from a lineage of stern authority figures who achieve their goals through corrupt means, Manami has learned that maintaining a good public image and having the right connections can allow one to get away with terrible things. Her social status provides her with both, and she is well aware of her privileged position. She demonstrates strategic thinking, indicating that she is not unintelligent.
Manami is very sexual and uses this to her advantage, manipulating others into doing her dirty work. She is extremely manipulative and spoiled, leveraging her father's wealth and influence to force others to comply with her wishes, often through blackmail or threats. Her ability to use emotions as a weapon makes her appear alternately as an innocent "good girl," leading many to take her side even when faced with her lies.
She manages to turn almost the entire student body of Nishidate High against Ayumu for an extreme reason, with only Miki and Sonoda remaining supportive of Ayumu. Manami speaks in the third person, referring to herself by her nickname, "Mana" (e.g., "Mana doesn't like that...").
