Sgt. Frog (ケロロ軍曹 Keroro Gunsō?, lit. "Sergeant Keroro") is a manga series by Mine Yoshizaki. It was later serialized into an anime TV series directed by Junichi Sato. Both the anime and manga are comedies that follow 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 he is captured while trying to hide in one of the family member's bedrooms. In both the manga and anime, Keroro is forced to do meaningless chores and errands for the family after his army abandons his platoon on Earth. The platoon has many failed attempts at taking over Earth.
The series takes its comedy from a combination of wordplay (particularly puns and homophones), physical humor, situational irony, breaking of the fourth wall, and numerous pop culture references (especially to Gundam, Kamen Rider, Super Sentai, Space Battleship Yamato, Dragon Ball, Neon Genesis Evangelion and many others, although when broadcast and published in the United States, they make references that American audiences would be familiar with like Ghostbusters and Men in Black). Various anime, games, manga, and other aspects of pop culture are parodied/referenced throughout the series as a bonus to older viewers. Both the manga and the anime are laden with pop-culture references, and even in the same story the references often vary wildly. The anime does not explicitly refer to Evangelion or other animations to which Bandai does not hold the copyrights, but only recreates the "feel" of famous scenes from these anime. The anime is much more detailed and direct in its Gundam references, however, since its animation studio, Sunrise, is a subsidiary of Bandai who does hold the rights to the Gundam franchise. Season 2 began on April 1, 2005, with episodes aired on Fridays instead of Saturdays. With Season 4's debut on April 7, 2007, episodes aired on Saturdays instead of Fridays. With Season 7's premiere on April 4, 2010 episodes aired on Sundays instead of Saturdays.
The main plot of the story focuses on the steadily deteriorating conditions of the Keroro Platoon, a group of five, frog-like aliens from Planet Keron of the Gamma Planetary System. The platoon’s mission is to invade and conquer Earth (known to the aliens as “Pekopon”), but fail miserably at each attempt. Sergeant Keroro (or Keroro Gunso) although being the leader of the platoon, is childish, incompetent, and would rather spend his time indulging in his hobby of making plastic Gundam models than take over Earth. Aside from Keroro, there are four other members of the Keroro Platoon: adorable but violent Private Second Class Tamama; bellicose yet tenderhearted Coporal Giroro; intelligent but mischievous Sergeant Major Kururu; and 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 human is Natsumi Hinata, whom he falls in love with; Keroro's human is Fuyuki Hinata, who considers the Sergeant his only true friend; Kululu's human is Mutsumi Saburo, who discovered him; Dororo's human is Koyuki, a fellow ninja; and Tamama's human is his equal in bipolar insanity, Momoka Nishizawa. All are tied to the Hinatas in some way throughout the events in the anime and manga.
Sgt. Frog is published in Japan by Kadokawa Shoten, serialized in the magazine Shōnen Ace, and was published in English by Tokyopop. The Keroro Gunsou manga began its monthly run in the weekly shōnen magazine, Shōnen Ace. The manga, first aimed at the older audience (teens/adults) from the first to the seventh volume, was toned down after the Anime started (Since the TV-series was a family show). However, the manga still maintains suggestive comedy that only the more mature audiences understand in present volumes. Tokyopop initially held the American rights to the Sgt. Frog manga until 2011 when the company ceased operations. By the time their publication ended, they had published 21 volumes. Their release of the manga have censored nipples drawn in some scenes, in order to get away from the OT (Older teen) rating and maintaining its Teen rating. Viz Media relicensed the manga for digital release on December 16, 2014. 
The anime series started airing on TV Tokyo in 2004 and ended in 2011. The anime is produced by Sunrise, and has been aired on Animax, TV Tokyo, and TXN. Seven seasons have been created during it seven-year run. Unlike the manga which is aimed at older audiences, the anime adaptation has been toned down to a level suitable for family audiences. ADV had previously announced they had acquired exclusive rights to an English dub of Sgt. Frog (for $408,000). However, on July 4, 2008, it was announced that rights to the English release were transferred to Funimation Entertainment.
ADV Films had originally added a brief teaser page to their website, announcing their licensing of the anime. The site turned to static before playing a short clip of Keroro dancing to "Afro Gunso," then leaving the message "hacked by the frog." This was followed by a press release from ADV on November 20, 2006, stating that they had licensed all Sgt. Frog properties (except the manga, which was already licensed by Tokyopop) for the US. It was once confirmed that the anime dub would be released on DVD in the United States in February 2007. However, ADV Films had never confirmed a release date. ADV announced at Comic-Con International 2007 that the US release date had been delayed because of TV negotiations but would not comment on which networks they were talking to. In a DVD included with the December issue of Newtype USA was an English-language trailer for Sgt. Frog released by ADV, with voices for Keroro (said to be voiced by Vic Mignogna), Natsumi, Fuyuki, Aki, and the narrator. ADV was 90% done on getting a deal with the show, though they created a separate team to work specifically on it that included people from Summit Entertainment (the company that worked with 4Kids Entertainment during the time they had Pokémon). They had dubbed three episodes, but they were dubbed three times because ADV created three different pilot-packages for television to see which one worked the best. They made an otaku/fan pilot, a mass-market pilot, and a kids' pilot. They received positive responses from three different networks. Cartoon Network liked the mass-market pilot, while Nickelodeon liked the kids' pilot. Nickelodeon told them that they would air the show if ADV got the merchandising rights. However, as of July 4, 2008, the English license for the first 51 episodes of the Sgt. Frog anime was transferred to Funimation Entertainment through a deal with Sojitz.
Funimation released a dubbed version of episode 12B as a test on YouTube to be reviewed by the viewers. Many instances of regional name changes were observed; Natsumi is renamed Natalie, and Giroro's cat was renamed "Mr. Furbottom," (despite being female). Additionally, the word Pekopon was changed to Planet Wuss, Pekoponians were referred to as Wussians, and Keron changed to Frogulon. The frogs' names remained the same as the Japanese version, though shortened by one syllable (e.g. Keroro changed to Kero, Tamama to Tama). The test episode had mixed reviews by fans involving the voice acting, jokes, and name changes.
At Otakon 2009, the first five episodes of Sgt. Frog were screened, where the original versions of the various names that were changed were used. The voice actor for Sergeant Keroro in the test video, Chris Cason, was swapped out for Sergeant Major Kululu's test actor, Todd Haberkorn. Kululu was changed to Chuck Huber, and the narrator also appears to have been changed. FUNimation stated at their panel that they were going to keep the anime as similar as possible to its Japanese counterpart, and claimed to only change references from Japanese pop culture (save for those Americans were already familiar with) to references from American pop culture. Those present at the showing seemed to enjoy the changes, and the reception of the official dub was very positive. On February 19, 2011, Funimation announced at Katsucon that they had licensed more episodes of Sgt. Frog.
According to FUNimation, as of February 2013, Sgt. Frog is "now on hiatus".
On July 31, 2009, Funimation added the first 4 dubbed episodes of the series to their online video portal. After a considerable delay following between the release of the first dubbed episodes, Funimation began making dubbed episodes other than the first 4 available on the portal. Currently, the first 51 subtitled episodes are available on the Funimation video portal and Hulu. The 51 dubbed episodes later expired, although they were all later placed back on the portal and on Hulu. The show is rated TV-PG on the DVDs and on Hulu. Unlike the other versions released outside Japan, the US version remains uncut.
The episode distribution scheme has been slightly changed from the Japanese Region 2 release. Although the first 51 episodes are known as "Season 1" in Japan, Funimation has divided the episodes into a "Season 1" and a "Season 2". The Season 1 Part 1 DVD set was released September 22, 2009. It contains episodes 1 through 13, Season 1 Part 2 was released on November 24, 2009, and contains episodes 14 through 26. Season 2 Part 1 was released on January 26, 2010, containing episodes 27-39. In addition, Season 2 Part 2 was released on March 30, 2010 containing episodes 40-51. The first two boxsets were re-released into one Season 1 set on March 29, 2011. The complete Season 2 set followed up on April 26, 2011. Season 3 Part 1 was released to DVD by Funimation beginning on July 26, 2011, containing episodes 52-65. Season 3 Part 2 was released to DVD on August 16, 2011 containing episodes 66-78. A complete Season 3 boxset containing episodes 52-78 was released on November 13, 2012. On all of the box sets, it states, "from the creators of the Gundam series". This is relatively incorrect because Sunrise did not create the Gundam series, they produced it, so it should say "from the studio that brought you Gundam". The creator of Gundam is Yoshiyuki Tomino.
All three seasons were available on Netflix streaming as of December 2011; however, the first two seasons, and the first half of the third, were removed without warning in January 2013, before the series was completely removed in April of the same year.
On January 7, 2014 it was announced that a new Flash anime television series entitled "Keroro" would premiere on Animax on March 22 of that year. Haruki Kasugamori is the director of the series at Sunrise and the animation studio Gathering is providing assistance with the animation. The series airs during the programming block, Keroro Hour, which airs both the series and reruns of Sgt. Frog. The series features new character designs and includes the characters, New Keroro, Tomosu Hinohara, and Myō Kaneami, all of which were originally manga-only characters. The opening to the series is "Keroro☆Popstar" (ケロロ☆ポップスター), performed by Mayumi Gojo. The flash anime ended on September 6 of the same year, with a total of 23 episodes.
Five full-length theatrical movies that were directed by Junichi Sato and produced by Sunrise were released:
- Super Movie Keroro Gunsou (超劇場版ケロロ軍曹 Chō Gekijō-ban Keroro Gunsō?) (2006)
- Chō Gekijōban Keroro Gunsō 2: Shinkai no Princess de Arimasu! (超劇場版ケロロ軍曹2 深海のプリンセスであります! Chō Gekijō-ban Keroro Gunsō 2: Shinkai no Purinsesu de arimasu!?) (2007)
- Keroro Gunso the Super Movie 3: Keroro vs. Keroro Great Sky Duel (超劇場版ケロロ軍曹3 ケロロ対ケロロ天空大決戦であります! Chō Gekijō-ban Keroro Gunsō 3: Keroro tai Keroro, Tenkū Daikessen de arimasu!?) (2008)
- Keroro Gunso the Super Movie 4: Gekishin Dragon Warriors (超劇場版ケロロ軍曹 撃侵ドラゴンウォリアーズであります! Chō Gekijō-ban Keroro Gunsō: Gekishin Doragon Woriāzu de arimasu!?) (2009)
- Keroro Gunso the Super Movie: Creation! Ultimate Keroro, Wonder Space-Time Island (超劇場版ケロロ軍曹 誕生!究極ケロロ奇跡の時空島であります!! Chō Gekijō-ban Keroro Gunsō: Tanjou! Kyuukyoku Keroro, Kiseki no Jikuu-jima, de arimasu!!?) (2010)
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 movie of Kaiketsu Zorori. Keroro and Tamama have appearances in the OVA of Lucky Star, and Kagami spends almost all her money on a grip-claw game trying to get a Keroro doll. The incoming Japanese game Monster Hunter Tri G is to have downloadable costumes of Keroro for the humanoid companions Kayamba and Cha-Cha.
- The English version of Sgt. Frog by Animax, entitled "Sergeant Keroro", has been broadcast in India (July 1, 2008), Indonesia (July 1, 2008), Malaysia (July 1, 2008), the Philippines
(July 1, 2008) and China. The only noticeable difference between this version and the original Japanese version is that "De Arimasu" is translated as "Sir, yes sir!" (which is also used in Funimation's subtitled version), Natsumi refers to Keroro as "Reptile" instead of "Stupid Frog" and Mois refers to Keroro as "Cousin" rather than "Uncle".
- In Hong Kong, it was initially broadcast by Cable TV, then by TVB. It was dubbed in Cantonese
separately by the two stations. The Chinese terms introduced in the Taiwanese version (mentioned later) were only applied in the TVB dub.
- In Indonesia, it was licensed and dubbed in Indonesian broadcast everyday on antv since August 11, 2008, named simply "Keroro". Only the first season was aired, but was shown in its entirety. In Indonesia, The manga has been licensed and released up to volume 22 by Elex Media Komputindo, under the title "Sersan Keroro".
- In Israel, the anime recently began airing on the "Arutz HaYeladim".
"De Arimasu" is translated as "iim kol hakavod" which means "with all due respect". The names were changed slightly – Keroro was renamed "Kerero", and his rank was changed to Captain (resulting in the show being renamed "Captain Kerero"), while Giroro's rank was changed to Sergeant (although in season 2 his rank was changed back to corporal). Also, Natsumi calls Keroro a stupid toad instead of a stupid frog. The Children's Channel aired the first season in its entirety, with the exception of episode 30.
- In Malaysia, the series has been broadcast since April 27, 2007, dubbed in Malay on ntv7, known simply as Keroro.
There are notable changes in the dubbing of the series. For example, Keroro does not address his human captors with honorifics. The series has aired since July 2008, dubbed in English with Malay subtitles on Animax, known simply as Sergeant Keroro.
- In the Philippines, it is dubbed in Tagalog and aired as Sgt. Keroro on ABS-CBN on June 4, 2007.
- In South Korea, the anime is aired on Tooniverse as 개구리 중사 케로로 (Gaeguri Joongsa Keroro , lit. Sergeant Frog Keroro).
As with most Japanese anime targeted to younger audiences there, the human Japanese names were changed to Korean-sounding ones. Aliens' names were generally the same (in pronunciation) as the Japanese names. It has become one of the most largely known Japanese anime in Korea, along with Crayon Shin-chan, Atashin'chi, and Death Note. It has many parodies to Korea in translation, with using famous Korean Internet memes at the time, and in the ending song of the fourth season, "You could say, violently going?", all main 12 voice actors did over 8 parodies to numerous things, such as "This is the first time I wanted to punch a girl (Death Note)" and "Is this... 'youth'? (Gundam)".
- In Taiwan, Keroro was broadcast in Mandarin on Cartoon Network and CTS. The names of Keroro and the other Keronians are transcribed in Kunrei-shiki romanization rather than into Chinese characters, and "Pekopon" is translated as "the Blue Planet" (Chinese: 藍星; pinyin: lán xīng), while Keroro's signature de arimasu is translated as 是也 (shì yě, literally "Is also").
- In Thailand, the anime is broadcast on TITV's Cartoon Club slot between 9.00 and 9.30 a.m. on Saturdays and Sundays under the title Keroro Lingo (เคโรโระ ขบวนการอ๊บอ๊บป่วนโลก). The manga is published by Siam Inter Comics under the same title.
- In the Middle East, the anime aired on Spacetoon. The names had a slight change, example: Keroro became Kero; Dororo became Doro etc.
- In France, the anime is aired on Télétoon under the title Keroro, mission Titar.
The human characters' names were changed from Japanese to French-sounding: the Hinata family is renamed as Monaté, with Fuyuki, Natsumi and Aki as Artus, April and Anna respectively. Momoka is called Garance Beller, Mutsumi as Mael while Koyuki is Énéa Azuma. "De arimasu" is translated to "Sauf votre respect" (or "sauf mon respect"), which translates as "With your/my respect". In the manga, published by Kana, the names are the same as the Japanese version.
- In Italy, the anime series was broadcast on Italia 1, beginning September 11, 2006 under the title Keroro. "De arimasu" is translated as "Signorsì"
("Yes, sir"), Mois called Keroro "Sir Keroro" in the anime and "Mio signore!" ("My lord") in the manga (published by Star Comics). Only in the anime "Stupid frog" was changed to "Brutto Ranocchio!" ("Ugly frog!"). After episode 76, the anime moved to Hiro with repeats airing on Cartoon Network and Frisbee.
- In Spain, the anime is aired in Spanish on Cartoon Network, starting on November 6, 2006 under the title Sargento Keroro. Other Spanish channels also emit the show, such as Canal Sur 2, Canal Extremadura Televisión, Telemadrid, Aragón TV, etc. In Catalonia, the anime is aired in Catalan on public broadcaster TV3 and in K3; and in Galician on public broadcaster TVG in Galicia. "De arimasu" is translated as "¡A la orden!" ("By your command") in the Spanish version and as "A formar!" ("Fall in!", in the military sense) in the Catalan version. The manga is published by Norma Editorial under the title Keroro. There are no name changes in either the manga or the anime.
- In Portugal, the anime is aired in Spanish and subtitled in Portuguese on Panda Biggs.
- The United Kingdom airs Funimation's release, and Tokyopop distributes the manga.
- In Serbia, the anime airs in Serbian on Ultra with some scenes censored. The manga has yet to be published in Serbian.
In 2005, the manga received the 50th Shogakukan Manga Award for children's manga.