During the Edo Period, 3 mysterious space capsules were sent down to earth. Fear that it might bring chaos to the earth, the humans at that time buried these 3 objects down beneath the ground and entrusted a piece of descriptive map to the Kamui family. Today, these 3 objects were awaken one by one. The first to awaken, Tri-Zenon, one of the Zenon Guardians is now driven by the descendant of the Kamui family, Akira Kamui, his brother Ai Kamui and his friend Kanna. Aliens who descend to earth with a purpose will now have to face Tri-Zenon. Akira Kamui and his brother Ai uncover a treasure buried on Bota Mountain, owned by the Kamui family that was described in an ancestral document. The treasure they discover is a giant robot called Tri-zenon. Later, two other robots, Gaia-zenoh and Arma-zenon, join forces, and the battle to protect the earth against the invader fleet Zeno-Palace begins. Why was this giant robot on Bota Mountain? Who are Zeno-Palace? Tri-zenon is a serious piece of robot animation that interweaves a fascinating mix of characters.