Suzuki, called "Rat" by associates, is the aging yakuza boss governing Treasure Town. His leadership reflects an older generation of organized crime, displaying tolerance toward orphaned street children Black and White, whom he considers integral to the city's ecosystem. Suzuki maintains a paternal bond with Kimura, a junior yakuza under his mentorship.

He directly imparts a core narrative theme to Kimura, stressing love's redemptive and sustaining force within Treasure Town's harsh reality. This philosophy positions him as a voice of experience opposing encroaching ruthlessness embodied by external threats like Snake.

Snake, a corporate developer aiming to demolish Treasure Town for a theme park, shatters the existing order. To eliminate resistance and seize control, Snake manipulates Kimura into assassinating Suzuki. This betrayal serves dual objectives: removing Suzuki as the old guard's figurehead and binding Kimura to Snake's organization through guilt.

Suzuki's murder acts as a catalyst, igniting Kimura's rebellion against Snake through remorse and vengeance. The chain of events arising from Suzuki's death underscores his narrative role in Treasure Town's overarching conflict. His relationship with Kimura also mirrors the film's exploration of brotherhood and loyalty, functioning as an adult counterpoint to the bond between central child protagonists Black and White.