The busty Naga the Serpent and the not-so-busty Lina Inverse are on their way to the mysterious Mipross Island. Accessible only once a year due to dense fog, the island once inhabited by elves is now home to relaxing hot springs. However, nefarious things are afoot! Stray jellyfish are seen throughout town, villains appear at every turn, and a strange frog creature lurks in the shadows – not to mention the all-too-often dreams that are plaguing Lina’s slumber. Naga and Lina must now find and put an end to an evil that spans time so that Lina can get to her ultimate destination: a mythical spring known to “grow” (err…”develop”?) what is thrown into it! The fate of Mipross Island and Lina’s chest now lies in their hands!
In the distant future, two species are at war to avoid extinction. Humans, who came from another world in search of a new residence, are now fighting against the Beasts, a human-like race who can morph into the shapes of animals. Wan of the Tiger Clan, Bud Mint of the Bird Clan and Mei-Mer of the Mermaid Clan are the three most powerful Beasts, and also the biggest threat to humans. The evil and demonic minions of the human race, V-darn and V-sion, have a plan: eliminate the three and acquire Gaia, the most valuable treasure of all. But the Beasts are after it too, and their Jinns, man-made clan totems, were created to protect Gaia no matter what. Things look up for the Beasts when they meet Tuttle of the Mermaid Clan and the little girl Yuni, who seem to hold the key for everything. Who will find the treasure first, the Beasts or the humans?
If you like Slayers The Movie, you'd probably K.O. Seiki Beast (aka ko century beast) since they both have similar art styles, and a slapstickish, cute, sort of sense of humor mixed with action/sword fighting, and ridiculous stuff.
I found the styles to be very similar.