Sensei Yang

Sensei Yang is a recurring character in "Ninjago: Masters of Spinjitzu" and is the main antagonist of the seventh season.

History
At an unknown point in time, Yang invented the technique of Airjitzu and would later take several students under his teaching, becoming infamous for his strict methods. However, unbeknownst to the public, he secretly trapped his students in his temple, and after his death, was converted alongside them into ghosts.

Ghost Story
Yang was mentioned by Misako to be the creator of Airjitzu.

The Temple on Haunted Hill
During the Ninjas' stay at the Temple to locate the Scroll of Airjitzu, he threw many obstacles (the fears of the Ninja) at them to make them stuck in the Temple. Later, it's revealed that he tested the Ninja if they're worthy for the Airjitzu scroll. However, as the morning came and the curse on Yang's Temple started to take effect on the Ninja, Yang's other students showed themselves, revealing them to be chained up, as they were imprisoned by Yang. The Ninja then quickly fled to the entrance, not wanting to suffer the same fate as Yang's students. They manage to reach the entrance, but Cole dropped the scroll mid-way and thus had to go back in to retrieve it, which caused him to turn into a ghost, with Yang's laugh echoing from the Temple.

Wishmasters
After his temple was torn out of Ninjago to help construct Djinjago, he left his temple to angrily confronted Nadakhan, claiming domain. However, the latter, unimpressed, promptly ordered Dogshank to shoot water at him and his students, forcing them to abandon the temple.

The Way Back
Yang's temple was strangely left still floating in the sky despite Jay's final wish. This may be due to Yang having "power" over his temple, being able to do many things with it.