Bonjiri is a supporting character who first appears as one of the children in the group led by Sachio, living in the impoverished borderland outside the city. In his youth, he is depicted as a chubby and timid boy who often finds himself in the company of Sachio and the other orphans. As a child, he is part of the makeshift family that forms around the former Team Nowhere, looking up to Joe and spending time in their community.

Several years later, in the events of the story set after a significant time jump, Bonjiri has grown into a young adult who runs a small Chinese restaurant. His establishment becomes the new gathering place and de facto headquarters for the now-grown members of the group, including Sachio, Oicho, and Santa. His personality remains gentle and perhaps somewhat passive, in contrast to the more aggressive tendencies of some of his childhood friends. Despite owning and operating his own business, his life is not free from the hardships of the district, as he remains connected to the underground world of Megalobox through his enduring friendships.

Bonjiri's role in the narrative becomes crucial as a catalyst for the central conflict of a major story arc. After a small-time Megalo boxer causes trouble at his restaurant and is injured by Sachio in retaliation, the boxer returns to trash the establishment and steal the deed to the property. This act of destruction directly endangers Bonjiri's livelihood and home, forcing Sachio to seek help from dangerous figures in the criminal underworld to get the deed back. Joe eventually learns of Bonjiri's predicament and intervenes, agreeing to a fixed match to reclaim the stolen document. This sequence of events places Bonjiri at the heart of the drama, serving as the victim of circumstance whose suffering motivates the actions of the other characters.

His key relationships are firmly rooted in the bonds formed during childhood. He shares a deep and long-standing friendship with Sachio, Oicho, and Santa, having grown up alongside them and weathered the hardships of their environment together. He is also closely tied to the protagonist Joe. After Joe's departure from their community years earlier, Bonjiri and the others are left to fend for themselves, leading to a complex mix of lingering affection and resentment. While helping Joe repair the old gym later on, Bonjiri expresses this internal conflict openly, admitting that a part of him wants Joe to return to fighting, while another part does not. This statement captures the ambivalent feelings of loyalty and hurt that define his perspective on their shared past.

In terms of development, Bonjiri transitions from a background figure among a group of children to a more prominent supporting character as an adult. He establishes a legitimate trade as a restaurant owner, showing a path of stability that contrasts with Sachio's struggling attempts to become a Megalo boxer. Throughout the challenges that arise, he demonstrates a resilient but non-confrontational nature, depending on his friends to navigate violent conflicts while providing them with a safe and familiar place to gather. As for notable abilities, Bonjiri is not depicted as a fighter or a participant in Megaloboxing. His primary skills lie in running his restaurant and maintaining the social hub for his found family, showing his value through provision and community rather than physical strength.