Ultraman Leo’s homeland, Planet L77 of constellation Leo, was destroyed during the invation by Alien Magma. Ultraman Leo escaped from Planet L77 and found his way to Earth, where he lived as a trainer at the Jonan Sports Center in his human form named “Gen Otori”.On the other hand, Ultraseven once more took up the duty to protect Earth succeeding Ultraman Taro and became the captain of Space Patrol Team MAC as Dan Moroboshi. During the battle against invaders Alien Magma, Red Giras and Black Giras, Ultraseven broke his leg, but was eventually saved by Ultraman Leo. Unfortunately, Dan’s right leg became impaired and lost his ability to transform into Ultraseven. Thereupon, Dan requested Gen to defend Earth in place of himself. Gen joined MAC on the recommendation of Dan, and started to fight al iens and monsters while training under Dan.