Sgt. Frog, known in Japan as Keroro Gunso (ケロロ軍曹, Keroro Gunsō, lit. "Sergeant Keroro"), is a Japanese manga series written and illustrated by Mine Yoshizaki. It was launched in Monthly Shōnen Ace in April 1999. The story follows the attempts of a platoon of frog-like alien invaders to conquer Earth. Sergeant Keroro, the titular character, is the leader of the platoon, but is at the mercy of a human family of three after being captured by them. Keroro is forced to do meaningless chores and errands for the family after his army abandons his platoon on Earth. The series was later adapted into an anime television series by Sunrise, which ran for 358 episodes from April 2004 to April 2011. A second 23-episode series was broadcast from March to September 2014.
地球侵略のため、隠密行動中だったケロン星人のケロロ軍曹は、日向冬樹と日向夏美に捕まってしまう。本隊の一時撤退により、地球に取り残されてしまったケロロは、そのまま日向家に居候することに…。そんなケロロのもとに集まったケロロ小隊の仲間とともに、ケロロは地球侵略を企む。彼らの作戦は果たして成功するのか…？