''[[http://jlucydaisuke.deviantart.com/gallery/24460003 Yin and Yang]]'' is a ''Manga/SgtFrog'' fanfic written by author [=jlucydaisuke=]. Then there was a sequel. Then another sequel. Then it became a series, with all in all three sequels, three side stories, and two oneshots.

''Yin and Yang'' is the first story. Kururu creates a SuperSoldier [[HomosexualReproduction using his and Giroro's DNA]]. Well, he attempts to anyways - the result is Kirere, who's subpar at everything except puzzles and [[WrenchWench mechanics]]. Deciding to raise her as a normal girl, Kururu introduces her to the platoon, who try to get used to the new addition to the team.

''[[http://jlucydaisuke.deviantart.com/gallery/24460005 Consequences]]'' is the second story. Kirere befriends a [[TheSlacker bill dodging mechanic named Haruki]], then gets kidnapped by a powerhungry Russian author, Nikolai Kezanstav. It includes the introduction of Romama, who harbors secrets as the captain of a mission gone wrong on Pekoponian a long, long ago.

''[[http://jlucydaisuke.deviantart.com/gallery/24460006 We Are Not Alone]]'' is the third story. Romama's teammates are discovered to be alive, and the platoon helps Romama find them, more or less because they want help for the invasion. Along the way, secrets are uncovered, Kezanstav appears again, with a wrong teammates of Romama who wants revenge.

''[[http://jlucydaisuke.deviantart.com/gallery/24460008 Paradise Is Where The Heart Is]]'' is the 'fourth story', but is really a collection of SliceOfLife stories about the whole OC and non-OC cast. Well, as SliceOfLife as you can get with a large cast, alien and human, and trouble brewing in every corner.

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!!This story provides examples of:

* AlternateUniverse: Several, both made by the author herself and by fans of the fic.
* BadassBookworm: Fujuju seems like a quiet guy at first... Only to end up being a dangerous pyromaniac.
%%* BattleCouple: Dororo and Lupapa.
%%* {{Brainwashed}}:
* DarkerAndEdgier: both 'Eliza - A side-story' and 'The Past has a Past, too...' depict events far darker than the ones of the main series, that usually tries to stay true to the spirit of the original series.
* EvilCounterpart: While not explicitly seen as such, Nikolai and Fuyuki are both occult-loving boy that met an alien.... only, it didn't end well for the alien, on Nikolai's part. Doesn't end too well for Nikolai either...
* HouseHusband: Fujuju cooks and cleans while his wife is busy presiding over the order of time.
* InterspeciesRomance: Let's see... There's Mahihi and Daisy, Romama and Aya, Fujuju and Botan, Rokiki and Mora, Haruki and Lavi, Porara and Mois, and even Kirere and Hiroshi, for one story.
* LastOfHisKind: Subverted. Rokiki first appeared as the last member of the Sankaku Tribe, only to discover that survivors remain scattered throughout the universe, and he's got a few descendants right here with him...
* {{Manchild}}: Haruki, who even looks younger than he is. Arguably Mahihi in flashbacks, and, of course, Keroro is Keroro.
* MayflyDecemberRomance: %%Fujuju and Eliza.
** Subverted with other inter-species relationship couples, as in their human form, Keronian ages the same rate as regular humans.
%%* MeaningfulName:
* MistakenForGay: Fujuju, who's a soft spoken HouseHusband.
* MoodWhiplash: Since chapters in "Paradise is Where The Heart Is" focus on different characters and plots, tone can also vary from chapter to chapter.
* ObliviousToLove: the Toro/Kire pairing is MADE of this trope, along with several canon pairings, such as Giro/Natsu, Kero/Tama, and of course Fuyu/Momo.
* PromotedToParent: Lupapa is perhaps the most egregious example of this trope, having taken care of her seven siblings since her parents' death. Frannie Martin also underwent this towards Oliver and Maggie.
* RetGone: The core theme of Episode 8 of 'Paradise is where the heart is'.
* ShoutOut: Oh so much.
** Doraemon, in the first lines of the first story
** Lupapa's design is based on ''Manga/{{Naruto}}'''s Kankurou, and her whole family are references to ''Naruto'' characters. Her name and thievery are based on ''Franchise/LupinIII''.
** The character of Fujuju pays heavy homage to Doctor Who. He's British, [[Creator/TomBaker wears a scarf]], lives in an old telephone box that's BiggerOnTheInside, and astonishes his human friends with alien technology.
*** Lampshaded once by Oliver.
---> '''Fujuju:''' We're going to make [the telephone box] fly.
---> '''Oliver:''' …Next thing I know you’ll be fighting trash cans and offering everyone jelly babies.
** So does Botan, the Time Lord...er, ''Time Bender''.
** The designs of twins Maggie and Oliver are loosely based on [[Music/{{Vocaloid}} Rin and Len]], while their sister Frannie's design is based on Miku.
* SilentSnarker: Romama, who lost his voice after years of not talking due to being in Kezanstav's mind control. He got better.
* SixthRanger: Kirere, after the first story, ends up becoming this for the Keroro Platoon.
%%* StableTimeLoop: A few.
* StalkerWithACrush:
** Romama, who secretly watches Aya's ballet practice from the rafters. Though now they have formally meet each other, he might not be one anymore...
** Also, Momoka towards Fuyuki, as is the norm.
* TeenGenius:
** Romama, who is already ranked Major at his age, for his fighting prowess.
** Kirere can also qualify, since she's building invasion weapons for the platoon already.
* TokyoIsTheCenterOfTheUniverse: Averted during the third fic: the members of the Romama Platoon are scattered all around the world. It may border AliensInCardiff in the case of Lupapa, given she ended up in the Amazon Rain forest.
%%* UsedToBeASweetKid: Nikolai Kezanstav.
* YoungerThanTheyLook: Kirere, who is, time-wise, around three years old. Biologically, she's eleven, [[PlotRelevantAgeUp thanks to her dad's Aging Ray Gun]].