Rayearth OVA - Episode 1

The Earth is in grave danger: Powerful inhabitants of the parallel world Cephiro have appeared in Tokyo and are anything but well-disposed towards our world. All humans have suddenly disappeared without a trace. Only the three friends Ikaru, Umi, and Fuu remain in Tokyo for mysterious reasons and must fight for the future of the Earth with legendary robots. But the battle cannot be won by force alone.