Mizuki Mauchi is a supporting character in the manga Shonan Junai Gumi. He operates as a silent subordinate alongside Nakagaki, and he is easily recognized by his surgical mask and quiet demeanor. This unassuming appearance causes others to underestimate him, but Mauchi possesses formidable fighting skills. During the Yokohama conflict, he proves his capability by defeating multiple gang members. Mauchi and Nakagaki together attempt to take over Shonan by ambushing Ryuji Danma's bus, and Mauchi becomes involved in the larger confrontation between the Shonan and Yokohama gangs. His role is that of a quiet but effective enforcer, and his actions contribute to the tension between the rival groups. His key relationship is with Nakagaki, as they operate as a pair. Beyond his combat prowess and association with Nakagaki, no further details about his background, personal motivations, or character development are available from the provided information.