The planet LaMetal begins a war of conquest with the Earth, and the only one who can defend the world from this threat is the Queen Millennia, a former princess of La-Metal who has made Earth her home.

The icy planet LaMetal, the rarely-seen tenth planet orbiting on the borders of the solar system, has an elliptical course which causes it to cross paths with Earth every 1000 years. Unfortunately, this near-collision wreaks great havoc and destruction on Earth, and every millennium civilization must rebuild itself, only to be struck down the next time. LaMetal's world is inhabited by a subterranean humanoid kingdom that abducts a large number of humans during the devastation on Earth, and enslaves them. To ensure this, a woman from LaMetal is dispatched to live on Earth for 1000 years to collect the humans in preparation for LaMetal's arrival. This millennium, the princess of LaMetal has been living on Earth, under the name of Yukino Yayoi. However, an unexpected development occurs: Yayoi has come to care for her family and friends on Earth, and decides to fight to protect the Earth from LaMetal.—Q. Leo Rahman

In the year 1999, Professor Amamori discovers a 10th planet in the Earth's Solar System, which he names La-Metal. He soon realizes that it is on a collision course with Earth. Queen Larela of La-Metal plans to abduct a human slave force before the expected destruction of Earth. The Millennial Queen Andromeda Promethium/Yukino Yayoi has spend 1000 years living on Earth under a cover identity, with the intention of establishing a colony for her home planet. She has her own family and friends on Earth, so she decides to save the planet from destruction.—Dimos I