Jinbei Shishido, an immortal second-in-command of the secret society UQ Holder, seized eternal life over 1,400 years ago by consuming mermaid flesh. Though his aging halted, his regenerative abilities remain limited, leaving scars accumulated across centuries. Classified as D-tier immortality, his existence persists unless decapitation and head destruction occur. Once a masterless samurai in feudal Japan, he shifted to martial arts post-Meiji Restoration, mastering Kenpo and diverse disciplines. His combat expertise spans millennia, stepping onto battlefields from the French Revolution to World War II and the Martian Rebellion, driven by a philosophy of direct action over detachment. Centuries of warfare honed his physical prowess, enabling feats like wielding the Gravity Blade at 50,000 times its weight and crushing foes with techniques such as Iron Arm Qigong. A spiritual awakening unlocked his signature ability, *Switcheroo*—spatial manipulation allowing teleportation and object-swapping within 350 meters. At its peak, this power reshapes his perception of reality into a four-dimensional gameboard, slowing time to a crawl as he manipulates or erases targets. Defensive applications include Spatial Isolation Chambers, while offensive maneuvers warp space itself to negate traditional defenses. Despite his lazy, carefree demeanor and aversion to leadership, Jinbei reluctantly mentors younger fighters, exemplified by training Juuzou Shishimi until the student eclipsed the master. Millennia of existence cultivate a detached outlook, accepting fatal outcomes with stoic pragmatism when battles turn unwinnable. Within UQ Holder, Jinbei’s strategic intellect and spatial powers prove instrumental in pivotal battles against foes like Shion Nagumo and Cutlass. He expands *Switcheroo*’s reach to planetary scales through consciousness training and aids in critical campaigns, including the final clash against Ialda, where his techniques pierce defenses like those of the White Titans. Interactions with allies reflect camaraderie laced with emotional distance, a hallmark of his ancient perspective. His history intertwines with figures like Evangeline A.K. McDowell, whom he aided in establishing UQ Holder. Though preferring minimal effort, his unmatched combat experience and reality-altering skills cement his status as one of the group’s most lethal assets.