Matsumi Kuro♀

Kuro is a second-year at Achiga Girls' Academy and one of Nodoka's childhood friends. Kuro was the children's mahjong club's number one player before it was disbanded. Afterwards, she kept the room clean for two years in hopes for that someone would show up and they could have fun together like they used to. She is the younger sister of Yuu Matsumi.

Kuro is a polite, cheerful, and has shown on several occasions to have a fascination with breasts. She also seems to be very optimistic, as she waited for two years for someone to restart the mahjong club. She has a very good relationship with her older sister. Kuro has described herself as the waiting type. However, it is hinted that she is also a little oblivious.

Kuro's main ability is to draw every single applicable dora: regular dora, kan dora, and red dora all gather into Kuro's hand. This comes from the fact that her mother told her to cherish her dora, which led to her keeping them in her hand, and subsequently began collecting them more frequently. More often than not, her starting hands do not contain that many dora, and throughout the course of the hand she will draw them, slowing her hand progression but also coming together consistently. This also means that her opponents cannot use the dora tiles to increase the power of their hands. However, her dora magnet ability has a drawback: if she discards a single dora tile, she will be unable to draw any dora for a set amount of hands. This drawback is a defining feature of Kuro's playing-style; she draws many dora tiles and refuses to discard them, leading her to break tenpai in order to keep dora.