Kei Watanabe is a fifth grade elementary school student. He has inherited the hunter's blood to hunt yōkai. To save the world from being destroyed, Kei Watanabe challenges a war against the yōkai.

The Great Yokai War: Guardians

Usagi has come to the airport to see Mamoru off as he heads to the US to study abroad, but someone shatters Mamoru's body to pieces. In shock, Usagi loses her memory and collapses, but a member of the super idol group the Three Lights is there to catch her. That day, the Three Lights were to star in a music festival. Usagi and friends were planning to perform as well, but a new enemy arrives. Calling themselves "Shadow Galactica," these enemies are Sailor Guardians aiming to steal Sailor Crystals!  At the same time, a mysterious young girl named Chibi Chibi and new Sailor Guardians, the Sailor Starlights, also appear, and a battle on an unprecedented scale begins.  Sailor Guardians vs. Sailor Guardians! Fittingly the Sailor Moon "final battle" has the future of the galaxy at stake and it starts now!!