A mysterious woman, Koyama Rei (Hatsumi Saki), was going around mahjong parlors looking for a certain person. She was looking for a topless woman playing mahjong. Takeshi Sugiura (Yoshida Kakumaru), who works part-time at the mahjong parlor "Tofu", fell in love with Rei at first sight and started searching for clues about the woman for her, but the owner, Shimura Kyosuke (Takemoto Yasushi), told him that she was a female mahjong player, Meiryuu, who was undefeated in the underground mahjong world. When Takeshi also found out that Meiryuu was Rei's mother, he asked the owner to let him meet Meiryuu. Then, when Rei and Meiryuu meet again, Meiryuu insists that she doesn't know her. However, Rei can't give up and recklessly asks Meiryuu to challenge her to a mahjong match...