Toshiro is a member of the Foot Clan and their main combat instructor. He trained Karai and later, instructed the wounded mutants Koya and Bludgeon, attempting to help them learn how to fight without flight or eyesight respectively.
He was concerned when Karai decided to go on a quest to find the sword of Takeshi Tatsuo. Later on, he was contacted by Natsu with news of her grandfather's impending ambush of Karai, and Toshiro brought the young woman along to stop it. He killed the would-be assassins before Karai had a chance to run into them.
Some weeks later, he accompanied Karai as she confronted the various yakuza bosses.