Chen Juanmin, also known by the nickname Weasel Chen, is a character from Souten no Ken who serves as an antagonist with a notable arc across different versions of the story. Before joining the Hong Hua Hui, the powerful Shanghai criminal organization, Chen lived as a poor fisherman. He eventually rose to become the Number Seven Boss within the syndicate. His most distinctive physical feature is a false hand, which conceals a firearm. He also bears facial scars, which were inflicted by the protagonist, Kenshiro Kasumi, following Chen's failed attempt to kidnap a man named Takeshi Kitaoji.

In terms of personality, Chen is portrayed as an opportunistic and ambitious individual. When the Hong Hua Hui's fortunes begin to decline, he is promoted to the Number Two position by the leader Tai-Yan. Rather than viewing the organization's troubles as a crisis, Chen reacts with visible joy, seeing the situation as a chance for personal advancement. He quickly decides that his first act as a higher-ranking boss will be to end the conflict with Kenshiro and the Qing Bang, demonstrating a pragmatic, if self-serving, approach to leadership.

Chen Jujanmin's role in the story diverges significantly depending on the medium. In the original manga, he meets his end when the Hong Hua Hui ship is sunk. As the vessel goes down, Kenshiro and other masters of Hokuto Shinken prepare to escape by breaking open the portholes, using a special technique to hold their breath for ten minutes. Chen, lacking this ability, desperately asks them to save him. Kenshiro refuses but forces Chen to use his prosthetic gun-arm to blast a hole in the ship's hull. Shortly after this act, Chen drowns, making his death a direct consequence of his own limitations and the harsh environment.

In the television anime adaptation, Chen Juanmin survives the sinking of the ship, unlike several of his comrades. Witnessing their deaths, he swears revenge against Kenshiro for the destruction of his associates and the Hong Hua Hui. Following Tai-Yan's defeat, Chen becomes the new leader of the organization. In this role, he demonstrates his ruthlessness by later shooting and fatally wounding a character named Pan Guang-Lin. His quest for vengeance culminates in a final confrontation with Kenshiro, where he is ultimately defeated and killed, bringing his story to a close through direct combat rather than by accident. His key relationships are thus defined by his loyalty to his fallen comrades in the anime and his enmity toward Kenshiro. His notable abilities include his proficiency with his concealed firearm and his survival instincts, though he is ultimately outmatched by the superhuman martial arts of his enemies.