Wu

Wu (also known as Master Wu) is one of The First Spinjitzu Master's sons. His brother, Garmadon, inherited the Oni Side, a.k.a. Destruction Power, while he inherited the Dragon Side, a.k.a. Creation Power. His nephews are Lloyd Garmadon and Cody Garmadon.

Season 1
He appears in Season 1 in all four episodes. He is responsible for keeping the ninjas' hope up.

Trivia

 * He seems to appear in all 4 episodes.
 * We don't know if in flashbacks or normally.
 * He might play a major role in keeping the hope up in Season 1.