A monster born from the solidified emotions born out of Earthling belief that rabbits live on the moon and pound rice cakes. Mochiron can retract his arms and legs to take on the shape of a mortar. It is incredibly strong and attacks by spitting fire from his mouth.

Mochiron wanted to eat real rice cakes, so it got on a spacecraft and flew to Japan. Mochiron went on to steal rice cakes around the country until it decided it wanted to eat rice cakes made with famous Niigata rice. On its way to Niigata Prefecture ZAT shot down Mochiron’s spacecraft, but the monster evaded their attacks and vanished into the mountains.

That night, ZAT’s former ally and descendant of the lunar civilization Yuko Minami came to convince Mochiron to return to the moon but the monster refused. Ultraman Taro then arrived and tested his strength against Mochiron but Taro lost. Father of Ultra appeared to berate Mochiron for his actions. Wanting to replace the rice cakes he had stolen and make amends, Mochiron turned into a mortar so Taro and the others could use it to pound out rice cakes. Finally, Mochiron is returned to the moon by Yuko and Father of Ultra.