Fo Fai made his first appearance in Battle Arena Toshinden, as an initially playable character. He also appeared as an initially playable character in Battle Arena Toshinden 2.
He is an ancient, bloodthirsty assassin, but often disguises himself as a kindly magician. He participated in the first two Toshinden tournaments and afterwards, visited Bayhou. He passed down his iron claws to the creature and trained him in his fighting style.
It is believed that Fo was then killed by Bayhou, since he carries a skull on his back that resembles the shape of Fo’s head and also because Fo's model used as a hidden outfit for Bayhou depicts him as a zombie with a bloody claw mark on his back.