Master of an aikido dojo and old friend of both the Yamato and Ninomiya families. When the feud broke out between Keisuke's and Ami's parents and they were too busy competing with each other, he watched the two children. Unbeknownst to the parents, Keisuke and Ami became good friends while they were young, though neither remembers knowing the other when they were young. After they grew older, Ōba decided to keep an eye on them. (Source: Wikipedia)