Mutekiou Tri-Zenon

Muteki-oh Tri-Zenon (無敵王トライゼノン) is a Japanese anime created by EG Film and directed by Takashi Watanabe. It broadcasted on TBS between October 14, 2000 and March 17, 2001.

Plot
During the Edo Period, 3 mysterious space capsules were sent down to Earth in the country of Japan. Fear that it might bring chaos, the humans at that time buried these 3 objects down beneath the ground respectively in Hokkaido, Tokyo and Kagoshima. Respectively in those regions, three individual families were entrusted to protect these objects, where the legacy was passed down through generation along with a descriptive map piece.

Now in present day, the Earth is under an invasion by a military organization called "Zeno Palace". Descendants of the Kamui family, Akira Kamui and his little brother Ai (followed by Akira's classmate, Kanna Uryu) departs from home to uncover the legacy to bring prosperity to their below-commoner poor lifestyle. But much more than they bargained for, they uncover one of the Zenon Guardians called Tri-Zenon, and the battleship Izumo. As the robots require 3 pilots with a battleship crew, its up to the hot-blooded Kamui family and the other legacy inheritors to save the Earth.