Mogo Yoku is the grandson of Hamato Yoshi's mentor, Mogo-San. Mogo-san traveled to New York City to track down Yoku and give him the family heirloom White Belt, but is devastated to find that Yoku has fallen in with a notorious criminal ninja organization called the Black Heart Gang. Mogo-san gives Splinter the belt and tells him to burn it, reasoning that its being destroyed is a better outcome than giving it to a traitor. However, after the gang's defeat and their leader's capture, Yoku reveals to his grandfather that he is is US government agent who infiltrated the Black Heart Gang. Mogo-san is relieved, and Splinter reveals that he never burned the belt, since he sensed good in Yoku.