Sensei Wu (formerly Techno Wu) is a major protagonist in LEGO Ninjago. He is the original Sensei of the Ninja, until his corruption to the Digital Overlord, being replaced by Sensei Garmadon. He is the youer son of the First Spinjitzu Master, and his status was evil, ally of the Overlord and Stranger (Pythor), until being freed by Garmadon First Appearance
Way of the Ninja
Sensei Wu approaches Four Weapons Blacksmith, and the Skeleton Army takes Kai's sister, Nya. He becomes a ninja, and helps get his sister eventually.
Wu spots Cryptor on a truck, sending Kai after him.