Cheerful Mimiko has a wonderfully strange family—a Panda for her Papa; and his son Panny, calls her Mom! When Panny follows Mimiko to school, he must pretend to be a teddy bear so Mimiko won't get into trouble. Despite his efforts to behave, Panny causes trouble in school and now the school is after Panny! Then, Panny makes a new friend, Tiny, a baby tiger who's wandered off from the circus.

During a motocross practice, Keisuke Jin is ambushed by two Myth Cyborgs created by a secret organization that's attempting to control Japan, G.O.D. (Government of Darkness). He transforms into Kamen Rider X, but little does he know that his battle is recorded and analyzed by King Dark, G.O.D.'s commander, to create a super cyborg. Other G.O.D. cyborgs are attacking all over Tokyo and in the middle of the crisis, the original four Riders return to Japan from different countries around the world. The five Riders unite to lead a counter attack against G.O.D.