Prior to the events of the anime's proper story, Shredder, Bebop, and Rocksteady obtain Dark MutaStones, and are easily dispatched by Turtle Saint. However, a crystalline cocoon, which contains Kris Mu's evil sister, Dark Mu, is nearing its hatching point.
At the end of the episode, Turtle Saint battles Dark Mu in outer space. The Turtles struggle to learn how to work together to control the Turtle Saint's movements, and Kris Mu holds Dark Mu from behind, allowing Turtle Saint to strike with the Mega Final Saint Blade, which seals Dark Mu and sacrifices Kris Mu and reverts them back to their crystals.
An action figure was released in Japan of Turtle Saint, which transformed from a chubby standard Ninja Turtle with the Turtle Saint's colors, into the form seen in the anime. There was also a Turtle Saint mini-figure, released in a couple of different multi-packs with other characters from the OVA.