Ryuichi, a boy who is an amateur at mahjong, decides to play mahjong against the novice killer "K" on the street, relying only on the tricks Araki taught him: "Surikae" and "Nanataiko"! Will Ryuichi be able to win?? Ryuichi is a hikikomori who is afraid to even face other people at the cash register at a convenience store, but before he knew it, he had developed the almost miraculous skill of shoplifting. One day, Ryuichi meets a man named Araki and is taken to a street mahjong venue in Marunouchi in the middle of the night...