Retsu is a
master of Shorinji Kempo. Just before the first World Warrior tournament, Retsu
was indefinitely suspended from his temple for being involved in too many fights.
He participated in the first world warrior tournament and
was defeated by Ryu.
While Retsu hasn't made an appearance in a Street Fighter
title since his debut, he plays a role in the back story of several characters
of the main storyline. Retsu is an a old friend
of Gouken's and is suggested to have
been present at the dojo during Ryu's and Ken's
training. In the UDON comics, Retsu is seen sparring with Ryu and is almost
beaten to death when Ryu goes into the Satsui no Hado, but Gouken stops him.
Retsu also defeated Dan
at some point (likely before Dan was kicked out of the dojo). In the original
Street Fighter, Retsu is the first opponent the player faces.