During Babylonian times an extraterrestrial named Babil landed on Earth due to a spaceship failure. He builds a tower with a new spaceship inside to return home, but the spaceship fails and he leaves the legacy of his knowledge to his future descendants. One of his descendants is Koichi, who leads a normal life together with uncles and his cousin Yumiko. But a meeting with Roden, a black panther that has the ability to take on the likeness of any person and to drain the life energy of enemies, changes the life of the boy forever. Led into the secret base, Koichi discovers his destiny and his mission - protect the Earth from the evil lord Yomi.