Fred, Daphne, Velma, Shaggy, and Scooby travel to Japan after winning backstage passes for a Hex Girls concert in the Juban district of Tokyo. (Plus, thanks to Daphne's family and the Hex Girls, the gang are able to ship the Mystery Machine across the pacific with them by plane.) Meanwhile, Usagi, Ami, Rei, Mako, Minako, Chibiusa, Mamoru, and the others are all very excited because Rei has won the chance to sing onstage with the Hex Girls at the aforementioned concert, and have therefore all been given VIP passes.
However, a hostile group of imperialists, and an old enemy of the Moon Kingdom known as the Black Moon Goblins have appeared. Long ago, the Black Moon Goblins attacked the Moon Kingdom in an attempt to conquer it and enslave all the people of the kingdom. The fight was fierce, but with the help of the outer sailor guardians, they were eventually defeated by Princess Serenity, Endymion, and the inner guardians, with the added assistance of two other sailor guardians known as the moon guardians: Sailor Titan, and Sailor Callisto. The Black Moon Goblin king, and what remained of his empire were eventually reborn into the present day, and vow to exact revenge on the Sailor Guardians, and take over the earth.
The girls and Mamoru team up with Scooby and the gang to solve this mystery, and find the two present day moon guardians (who turn out to be Daphne and Velma) and the legendary silver heart crystal to help them defeat this new threat
