Premier member of the reigning champion Mahjong team, Ryuumonbuchi, and one of the most idolized yet feared players in the game. She is said to be possessed by a demon when playing; she even outranked a professional Mahjong player at a previous tournament. She is also the key player that brings an end to Kazekoshi's winning streak. She has a bad habit of wanting to crush her opponent's pride.

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Her mahjong playing style pressures her opponents and her abilities can prevent them from reaching tenpai. This, together with the mahjong move she favors most, Haitei Raoyue or "last tile win" is a combination that slowly drives her opponents into despair. Haitei Raoyue's literal meaning is "to scoop up the moon from the seabed." Her abilities include being able sense when her opponents are in tenpai and the approximate value of their hands. She usually goes for big hands.

She is Touka's cousin, their relationship akin to those of siblings due to the amount of time they have spent together. She prefers to not be seen as a child, despite their small stature and her childish personality. She acts in a very friendly manner, always wanting to make friends with everyone she meets and in hopes of being treated lovingly.

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This desire most likely roots itself from the fact that her parents died early in her life, leaving her alone under the supervision of the Ryuumonbochi family. She is kept isolated for vague reasons; Touka mentioned that she was told by Koromo's Father to particularly "not get close to her". Despite this, she appears to hold quite a strong, stable relationship with Koromo.