Sgt. Frog, known in Japan as Keroro Gunso (Japanese: ケロロ軍曹, Hepburn: Keroro Gunsō; lit. 'Sergeant Keroro'), is a Japanese manga series written and illustrated by Mine Yoshizaki, which is published and serialized in Kadokawa Shoten through its Monthly Shōnen Ace magazine since 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 aired from April 2004 to April 2011. A second short-form series aired from March to September 2014. A new anime project was announced in April 2024 to celebrate the 20th anniversary of the original anime, and was released as a film in June 2026. A new anime television series premiered in October 2026.
The manga was released in North America by Tokyopop from March 9, 2004, to May 10, 2011, and later digitally by Viz Media since December 2014. An English dub of the anime series aired on Animax Asia in 2008 with the title Sergeant Keroro; with Funimation releasing a second 78-episode English dubbed version in North America in 2009, which aired as Sgt. Frog on Crunchyroll, Funimation and later on Netflix, as well as on DVD sets. Discotek Media re-released the Funimation dub in SD Blu-ray in 2021.
In 2005, the manga received the 50th Shogakukan Manga Award for the children's manga category.
Contents
Plot
The Keroro Platoon is a group of five, frog-like alien soldiers from Planet Keron. They mean to conquer "Pekopon" (their name for "Earth") but fail each every time they try. Their leader, Sergeant Keroro, is incompetent and has little interest in conquering Pekopon. Instead, he likes making plastic Gundam models, watching TV, or coming up with schemes to make money. The four other members of the platoon are: the adorable but violent Private Second Class Tamama; the bellicose yet tenderhearted Corporal Giroro; the intelligent but mischievous Sergeant Major Kururu; and the disciplined but traumatized Lance Corporal Dororo.
The largest obstacle in the way of their mission is the Hinata Family, who must take care of the Keroro Platoon due to the Keron Army deserting the latter on Earth. Keroro is kept busy with manual labor and constant abuse, primarily from the family daughter, Natsumi. Each member of the platoon finds himself in the care of a human: Giroro's is Natsumi Hinata, whom he falls in love with; Keroro's is Fuyuki Hinata, who considers the sergeant his only true friend; Kururu's is Mutsumi Saburo, who is just as mischievous as him; Dororo's is Koyuki Azumaya, a fellow ninja; and Tamama's is Momoka Nishizawa, who is just as bipolar as him. All are tied to the Hinatas in some way throughout the events in the series.
Media
Manga
Written and illustrated by Mine Yoshizaki, Sgt. Frog is published and serialized by Kadokawa Shoten through its Monthly Shōnen Ace magazine, and is published in English by Tokyopop. The manga, first aimed at the older audience (teens/adults) from the first to the seventh volume, was toned down once the anime adaptation started (since the TV series was a family show). However, the manga still maintains its suggestive comedy that only the more mature audiences would understand in present volumes.
Tokyopop initially held the American rights to the manga until 2011 when the company ceased operations, which had 21 volumes published by the time their publication ended. Their release has censored nipples drawn in some scenes, in order to get away from the OT (older teen) rating to maintain its Teen rating. Viz Media relicensed the manga for digital release on December 16, 2014.
To commemorate the 20th anniversary of the series, the November issue of Shōnen Ace announced the launch of a new manga on October 26, 2018. Titled Chō Keroro Gunsō UC: Keroro Robo Daikessen (Super Sgt. Frog Ultra Cool: Keroro Robo's Epic Climactic Battle), the series is created by Yūtarō Shido, while Mine Yoshizaki is credited as the original author.
Anime
An anime television series produced by Sunrise aired from 2004 to 2011, on TV Tokyo and its affiliates. A second short-form series aired from March to September 2014, and a third series premiered in October 2026.
Spin-offs and guest appearances
Spin-offs include a manga called Musha Kero that has recently been adapted in the anime. The series has spawned a magazine called Keroro Land that promotes toys, games, media, and events based on the manga and anime.
Sgt. Keroro, Tamama, Giroro, Dororo and Kululu make cameo appearances in the 1st movie of Kaiketsu Zorori.
Keroro and Tamama have appearances in the OVA of Lucky Star, and Kagami Hiiragi spends almost all her money on a grip-claw game trying to get a Keroro doll.
Japanese action RPG game Monster Hunter Tri G has downloadable costumes of Keroro for the humanoid companions Kayamba and Cha-Cha.
Keroro, Giroro, Tamama, Kururu and Dororo appeared as playable characters in the Nexon mobile game Kemono Friends. The characters were added during a collaboration event. Like the animal characters in the game, the Keronians take the form of human girls. Enemy monsters called "Ceruleans" also appear, taking the forms of Natsumi and Keroro herself. Mine Yoshizaki, the creator of Sgt. Frog, is also the concept designer of the Kemono Friends franchise.
Video games
Many of the video games were only released in Japan, but there were others released in Korea.
Reception
In 2005, the manga received the 50th Shogakukan Manga Award for children's manga.