This is episode 0, the prequel to the main Keroro Gunsou anime series. KeroZero was shown in theaters with Keroro Gunsou Movie 4.

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...

Seeking to unlock the mystery of a strange stone statue that looks exactly like their Sergeant, the members of the Keroro Platoon find themselves engaged in a great adventure.

Another Kiruru appears in the South Pacific, but it was defeated by two unknown entities that look like Keronians, with subtle differences. Meanwhile, Keroro and the gang goes for a trip sponsored by Momoka to a private island. There, an alien named Meru, who claims himself as the prince of the deep sea, captures them, and aims to make Natsumi his princess, and that they had captured Keroro, who pleads to them to assist the Keroro Platoon, only to be kicked out.

TVアニメ「ケロロ軍曹」の中から、大人気“武者ケロロ”エピソードをセレクション! 　　伝説の古代兵器を回収すべく、いざ戦国ラン星へ! 　　武者ケロ小隊、ここに参上!!乞うご期待の前編であります!! 　　【3話収録】 　　■第1話「武者ケロ 壱の巻 伝説の勇者 でござそうろう」 　　ケロン軍伝説の古代兵器を回収するため、戦国ラン星へいくことになったケロロたち。その時、星の支配者ヴァイパーも伝説の古代兵器を手に入れるべく動き出していた。 　　■第2話「武者ケロ 弐の巻 爆笑!戦国お笑い合戦 でござそうろう」 　　2つ目の伝説の古代武器を手に入れるために『水着お笑い合戦』に出場することになった武者ケロ一行。そんな中、ギロロは『水着お笑い合戦』に出場しようとする夏美と瓜二つのお夏という少女に出会う。 　　■第3話「武者ケロ 参の巻 大爆発 桃姫危機一髪!! でござそうろう」 　　戦国ラン星に眠る5つの伝説の古代兵器。武者ケロ一行は、3つ目の古代兵器を求めてモモ城へと向かい、そこで桃華そっくりの桃姫に出会う。しかし、そこにはやはり武者ヴァイパーの魔手が…。

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...

keroro! A brand-new campaign to invade Pekopon begins!

《Keroro军曹》是日本的一部喜剧动漫作品，原作漫画版作者为吉崎观音，原是针对成人读者的漫画，其後由日升动画公司改编的动画却吸引大量儿童读者。动画版于2004年4月3日至2011年4月3日在日本播出，一共七季358集，目前已经全部播映完毕。而军曹亦评为无线版《福星小子》。香港无线电视于 2006年7月3日首播，目前已播到第七季

《Keroro军曹》是日本的一部喜剧动漫作品，原作漫画版作者为吉崎观音，原是针对成人读者的漫画，其後由日升动画公司改编的动画却吸引大量儿童读者。动画版于2004年4月3日至2011年4月3日在日本播出，一共七季358集，目前已经全部播映完毕。而军曹亦评为无线版《福星小子》。香港无线电视于 2006年7月3日首播，目前已播到第七季

Yu-mi applies to a marine outfit to become their first female member. Finding out about their NO woman-policy, she pushes herself to the extreme and fils a petition. After overcoming many obstacles, she is finally accepted for her outstanding performance. However, conflicts never cease between sergeants and Yu-mi, who’s new to the tradition and culture of the marines. Following the sudden death of a trainee, Sergeant HA, she is appointed to the head of the team. Highly motivated Yu-mi loses her troupe's trust after losing IBS. The team is in danger of dissolution due to the loss of a magazine.