The Undertaker Leader commands the Undertakers, a parkour battle crew based in Odaiba within Tokyo's isolation bubble. His crew competes in parkour tournaments against rival groups, bartering their victories for essential supplies. Backed by an unspecified powerful sponsor, he is equipped with advanced, high-performance boots specifically engineered to enhance combat effectiveness during gravity-defying competitions. His leadership is marked by ruthless tactics and unsportsmanlike conduct, defining the Undertakers through their aggressive contest strategies.

Physically imposing, the Undertaker Leader's eyes and much of his face are obscured by a distinctive mask; he has short black hair. His tactical attire includes fingerless gloves. He relies entirely on a built-in voice assistant device integrated into his hand, which handles all vocal communication on his behalf.

Functioning as an antagonist to protagonist Hibiki and the Blue Blazes crew, his hostility escalates during a tournament. He orchestrates the capture of Makoto, a Blue Blazes member, suspending her above a dangerous gravity rift. He threatens her safety to coerce the Blue Blazes into a high-stakes competition against the Undertakers, demonstrating his willingness to use coercion and exploitation for dominance. The Undertakers initially gain an advantage through underhanded methods but are ultimately defeated by Hibiki and Uta's combined efforts.