Shuden, a Japanese girl, emerges during Team Wild's recruitment at Elkatraz—infamously dubbed Hell's Island. There, she undertakes a grueling test: navigating a treacherous, banana-skin-laden course within five minutes while maintaining over 85 percent target accuracy. Though she attempts the challenge, she falls short of the passing standard set by Japo.

Undeterred, Shuden secures her place on Team Wild shortly after the team faces setbacks from a failed Nicaraguan Special Forces rescue and their own mission ambush. She achieves this by outmaneuvering Dantotsu in a poker game, showcasing strategic skill distinct from direct combat prowess.

As a member of Team Wild, Shuden joins critical operations aboard the hijacked vessel Double Sea. During the final mission to rescue hostages and confront the terrorist leader Nagashima (Wolf), she fights alongside teammates Looks and Japo against Wolf. In this decisive confrontation, Shuden sacrifices herself. Her action aids the effort to save Japo and eliminate the threat, ultimately contributing to the safe rescue of all hostages before the ship's destruction.