Sensei

Sensei is the judo teacher of Gwen. In Ben 10 Returns: Part 1, he was moderating a sparring match between Gwen and an unnamed student. He made a cameo in It's Not Easy Being Gwen.

Ben 10: Alien Force

 * Ben 10 Returns: Part 1 (first appearance)

Ben 10: Ultimate Alien

 * It's Not Easy Being Gwen (cameo)