Yè Ziying is a streetwise youth, approximately 12-14 years old during the events of *Souten no Ken*. He operates in Shanghai alongside his father, Yè, a former Qing Bang triad member. Together, they encounter and assist Kenshiro Kasumi upon his return to the city. Their aid comes during a period of conflict with the rival Hong Hua Hui organization, helping Kenshiro navigate Shanghai's dangerous underworld. Demonstrating resourcefulness, Yè Ziying steals Kenshiro's bag during their first meeting; this act ultimately leads them to reunite with his father, an old acquaintance of Kenshiro. Functioning as Kenshiro Kasumi's sidekick, a role paralleling Bat's relationship to the 64th Hokuto Shinken successor, Yè Ziying supports Kenshiro's efforts against the Hong Hua Hui's oppressive activities, including their brutal "Game of Death" fighting contests. His documented background centers solely on the original *Souten no Ken* timeframe.