Watch Keroro Online

This was the 14-minute movie that was screened in theaters with Keroro Gunsou Movie 3. It became the prequel to the Mushakero in season 5 of the main Keroro Gunsou anime series. It takes place in Ranstar where the Keroro platoon are up against the Vipers. The whole setting of Ranstar is based on the Sengoku Era of Japan, and all characters are dressed in that fashion.

One day, a stone carving bearing an uncanny likeness to Keroro arrives at Fuyumi's place. To solve this mystery, the Keroro Squad travels to the isolated and mysterious Easter Island. There, they meet harmless spirits known as Mana, and the odd twins Io and Rana. Lastly, there is Akuaku, a legendary evil spirit recently awoken from its long sleep.

Mysterious giant beings called "Ryū no Shippo" (Dragon Tails) appeared across the world. Due to the danger it could bring, the Keroro Platoon did a worldwide research on the Dragon Tails, but Tamama suddenly disappeared during the research. Because of this, the whole platoon started their search for Tamama and ended up in Mont-Saint-Michel, France where they met mysterious girl named Sion, who holds the mysterious Ryū no Hon (Dragon Book). But little they know about the secrets about her and the worldwide calamity that would destroy the entire world, as they know it...

The movie begins with Fuyuki Hinata and the Keroro Platoon exploring an abandoned temple in the mountaintop city of Machu Picchu in Peru. While on the exploration, Keroro accidentally sets off a trap, and by chance they find a hidden chamber with a large blue crystal in the center, on a stand that has a key in it. Keroro leans on the key, causing the room to activate a mysterious machine, this caused the entire temple to shake. As soon as the group realized what was happening, they run out of the room. While running, Keroro accidentally loses his Kero Ball while Fuyuki catches a fleeting glimpse of a glowing young woman as he is running out, and tells Keroro that there was a girl in the room, but he is forced to leave the room before he can say anything else. The group successfully escapes, while the girl (now sprouting a pair of glowing wings) watches them leave - while back in the chamber, something is growing within the crystal...

During a vacation Natsumi is visited by two male and female aliens named Meru and Maru. After becoming the Deep Sea Princess, Natsumi gains feelings for Meru who is haunted by his traumatic past. Having grown accustomed to Natsumi's title, the Keroro Platoon expects a calm vacation; however, their vacation is cut short and turns into a fight for survival as an alien creature that Fuyuki has adopted reveals itself to be the enemy of the kingdom and now sends creatures of mass destruction to assassinate Natsumi, and any who stand in their way.