Mondo is a spy from an ancient warrior clan and an old acquaintance and rival of Fo Fai. He had entered the first Toshinden tournament in order to collect information about the Secret Society for his client. Just as his client was about to attack the Secret Society, Mondo had received an invitation to the second tournament. His client tried to hold him back, telling him to discard the invitation, but Mondo ignored the restraint and entered the tournament. At the end of the event, the Secret Society had fallen. He also participated in the third tournament, hosted by the Organization.

Afterwards, Eiji Shinjo became the head of the Gerard Foundation and when he learned about the power of the Four Sacred Arms, he started hunting for Mondo, since he carried one of them. He was also targeted by Genma, who also sought the power of the Four Sacred Arms. It is assumed that before the fourth tournament was held Eiji managed to catch up with Mondo, since Eos, one of Eiji's fighters, carries his spear.