Matsugorō Totsuka is a supporting character in the anime Koiko no Mainichi, which is based on the manga by George Akiyama. He is a member of the Menzō-gumi, a yakuza organization, and serves as a subordinate and loyal follower of the protagonist, Sabu. Matsugorō is portrayed as a dedicated and earnest figure within the group, often acting as a reliable right-hand man. His background includes an attempt to leave the yakuza lifestyle behind when his girlfriend, Kayo, became pregnant. He decided to take responsibility by marrying her and taking over her family's bicycle shop. However, he found it difficult to adapt to a legitimate life and eventually returned to the yakuza world.

In terms of personality, Matsugorō is characterized by his deep sense of loyalty and devotion, particularly toward Sabu, whom he respects as a senior brother figure. This loyalty drives his actions and decisions throughout the story. Despite his return to the yakuza, his motivations are rooted in his desire to protect and support those close to him, especially his family and his senior. His relationship with Kayo is a central aspect of his character arc; she is the one who grounds him and represents his aspirations for a normal life, even when those aspirations prove difficult to maintain. Within the group, Matsugorō's role is that of a reliable subordinate and occasional source of comic relief, though he also participates in the group's activities and confrontations. His development focuses on the tension between his desire for a peaceful family life and his ingrained sense of duty and belonging to the yakuza world. His notable abilities are not explicitly highlighted, but as a yakuza member, he is presumably capable in physical confrontations and familiar with the codes and operations of the organization.