Tsuyoshi Aiba is a stockbroker who buys and sells stocks for clients, working alongside colleagues including Hitomi Yamazaki and Haruhiko Emoto. His life changes irrevocably when his friend Kurihara commits suicide after being deceived into helping Chinese mafia member Lin Haifeng acquire stocks tied to a major Tokyo waterfront development project. Kurihara's death fuels Aiba's central motivation: to avenge his friend by stopping Lin's scheme to gain majority control of the waterfront company and turn Tokyo into a criminal gateway dubbed "New Hong Kong."

Driven by loyalty and a sense of justice, Aiba commits himself to blocking Lin's path to majority shareholder status. He leverages his stock market expertise, engaging in strategic financial maneuvers to counter Lin's acquisitions. This includes a direct, high-stakes battle of stock purchases against Lin's enforcer, Ba Kou, visualized with intense, action-oriented imagery despite the conflict's non-physical nature.

Aiba demonstrates significant initiative and occasional impulsiveness in his pursuit. He travels to Hong Kong to investigate Lin's operations firsthand, a move showcasing his determination but also leading him into peril. This results in a physical confrontation and chase with Ba Kou through a warehouse district, where Aiba survives through evasion and hiding.

Throughout his efforts, he receives support and trust from Gen Daimon, the vice-director of his brokerage firm. Daimon acknowledges Aiba's instincts about Lin's threat while cautioning him against rash actions like the unplanned Hong Kong trip. Aiba's character is marked by passionate dedication to his friends and his profession, embodying traits of persistent, energetic protagonists focused on righteous causes. His actions consistently focus on disrupting Lin's financial takeover to achieve personal vengeance for his friend's death.