Koshi Inuzuka is an Ordinary High-School Student, handsome and intelligent with dreams of moving into the legal profession... but he's also a member of a martial arts family headed by his huge, muscular father, who persistently looks down upon his chosen path. Said father is very much pleased when Momoko Kuzuryu, the tiny, annoying, love-struck Genki Girl daughter of another martial arts family, seeks out Koshi to sire a child capable of mastering her family's most powerful techniques. Naturally, this not-so-subtle strongarming into Arranged Marriage (of course supported by the fathers of both youngsters) and newfound accompaniment of a pink-haired, Kamen Riderhenshin pose-copying, totally enamoured imbecile is not to the taste of violence-phobic and martial arts-hating Koshi.However, they soon find the reasoning for the Arranged Marriage goes a lot deeper than they thought - Koshi and Momoko are part of a plan to form a bond of blood between twelve Zodiac-related martial arts families and prevent a colossal war between two warring factions of said families, one headed by the Dragon-based family of which Momoko is a member, and the other headed by the Dog-based family that includes Koshi. Naturally, some of the families view such a war as a perfect opportunity to rise above the others - and send assassins after Koshi to ensure the marriage does not proceed.So far, a reasonably typical martial-arts-and-romance manga and anime. Now, factor into the equation that everything in the show except Koshi is bordering on the insane, and anything and everything is taken to ridiculous extremes.The entire show possesses the subtlety of a hard kick in the face, and packs itself to the rafters with a horde of bizarre nutcases protecting Koshi, baying for his blood, falling madly in love with him and each other and generally going Super-Deformed a lot and doing big shiny martial arts somewhere between Fist of the North Star and Dragon Ball that transform the whole affair into some giant amorphous blob of EcchiLove Dodecahedron borderline-Gag Series romantic comedy with lots of people beating each other up in completely over-the-top ways on a regular basis.The title is based on the tongue-twister, "Sumomo mo momo, momo mo momo, sumomo mo momo mo momo no uchi." No, notthatMomo, and not that Sumomo.
If you're really interested, the translation is "A Japanese plum is a kind of peach, a peach is also a peach, both Japanese plum and peach are kinds of peaches."
Affectionate Parody: It's very hard to see how over-the-top the series is without thinking that it has to be an Affectionate Parody to some extent of both martial arts and Harem Anime.: Although this is lost a bit in the anime, which introduces Tenka a bit later and then plays up the seriousness of the zodiac family feud.
Against the Setting Sun: Parodied - Momoko and an adversary have a moment of newfound acceptance and friendship after a fight as the sun sets... and promptly forget to save Koshi from man-eating sea snakes in the background.
Ahoge: Momoko has a self-made ahoge. Perhaps she subconsciously realized her personality required one. She briefly tries changing her hairstyle to attract Koshi's attention — by adding more ahoge!
Bears Are Bad News: As bears are used in-story as the yardstick for how effective a martial artist is, it's bad news when Koushi is brought before one to show just how strong he is... or is not. Also, when Iroha causes a mass escape at a zoo to assassinate Koushi and Momoko, guess what is the most dangerous of the escaped animals?
Born in the Wrong Century: Koganei Tenga states that he can't forgive himself for doing this. It's highly implied that he feels this way because the strongest martial artists, that developed martial arts by themselves, lived in the past.
Err... well... close. Tenka is from the Tiger family and thus takes on catlike qualities, such as playing with a ball he is convinced talks to him called Becky. At one point he is defeated by being distracted by cat toys and his fear of clear water bottles or "nekoyoke".
Tenka, after his Heel-Face Turn, uses this against his younger brother quite effectively. It's unknown whether the other Koganeis also act like this.
Celibate Hero: Koshi doesn't have time for romance, as he is studying to become a lawyer. Possibly not celibate so much as just having the sense to want nothing to do with Momoko's 'seductions'. He certainly seems approving enough of Sanae in general.
Clothes Make the Superman: Uma Kamen's outfit. It focuses power into certain parts of her body, and thus inverts the trope by becoming more effective the less of it that is worn. It's at its most powerful when all she wears is the boots.
Held up as an ideal by Momoko's father, and it's strongly hinted that he and Koushi's father went through this process as well (although it's unclear if either won said fight or if it was a draw).
Determinator: Koushi later in the manga, where he refuses to die in a martial arts duel so that he can fulfill his dream of becoming a prosecutor. His father, shocked that Koushi even had it in him, breaks down in Manly Tears.
Does Not Like Shoes: Highlighting her life-long martial artist training, Momoko very rarely wears shoes, even during school. Later inverted when she finally does get a pair of shoes from Koushi, the first gift he gives her. She wears them any time she isn't fighting, despite the fact that they're several sizes too big. When Koushi throws them out due to being worn out, she throws out a Death Glare potent enough to make both of their fathers, two of the strongest martial artists alive, scared.
Fair Play Villain: Koganei Tenga could've killed both Koushi and Momoko, as weakened as they were by the effects of the poison, yet he wanted to have a fair fight.
Fallen Princess: Iroha, who was doted on by her father and never really bothered to learn about the basics of day-to-day living, or for that matter anything outside of clan disciplines. She discovers the downsides to this when she tries to earn money for her clan via part-time jobs.
The Good Guys Always Win: The main reason why an emotionally broken Momoko could win against an equally strong, yet much faster and undoubtedly way most experienced and matured than her, Koganei Tenga.
Except, you know, his being distracted by an extremely mad Koushi.
Good Is Dumb: Iroha — fearsome Ninja, ruthless fighter, not averse to drugging polar bears to assassinate people... until her Heel-Face Turn and subsequent transformation into a tiny schoolgirl with a voice two (very annoying) octaves higher and designs on Koshi's affections. Doesn't make her any weaker though. This turns out to be an inversion, as she was completely overwhelmed by Koushi before said Heel-Face Turn... in his sleep. Iroha ends up losing every single time she tries to do something until she changes sides.
Heroic Build: Many of the older male martial artists, such as Momoko and Koushi's fathers, are build like this. A few younger ones (like Sanae's would-be fiance Hikari) also have a similar physique.
Hilariously Abusive Childhood: Shintarou Inoue. While Shintarou's father does love his son, he's either somehow completely ignorant or in denial about the fact that he has a daughter instead. This results in him smacking his daughter around for being attracted to men, trying to convince Shintarou to participate in orgies because having multiple women is a sign of manliness, and Shintarou continuing to masquerade as a male because she worries that her father wouldn't love a daughter as much.
I Was Quite a Looker: Kimie Nakajima, who looked much like her granddaughter Sanae when younger and is a Miniature Senior Citizen now. The head of the Inoue clan had a crush on her when he was younger, and was quite shocked to see how she aged.
At one point it's quite unbelievably claimed that Iroha is 15. On top of this Hanzo spends clan rebuilding money on a distinctly dodgy-looking DatingSim...
Momoko is the same age and a similar build to Iroha. Then there's when Momoko asks point blank whether Koushi prefers women with well-developed figures. He immediately clams up and looks away, suggesting one of Momoko's (and Iroha's) major stumbling blocks is that Koushi isn't a lolicon.
Loony Friends Improve Your Personality: Koushi never wanted an Arranged Marriage or to be surrounded by lunatic martial artists bent on killing/loving him. But after Momoko finally admits she knows he doesn't love her, Koushi acknowledges that his experiences have broken him out of his fear of confronting other people (even if he's still a physical coward.)
Noble Demon: Tenga, who disdains his sister Tenten's devious ways and her use of poison - in fact, rather than hold onto the portion of the antidote for Tenten's poison until he is defeated, he gives it to Koushi and Momoko so that he can have a proper fight afterwards.
Raised as the Opposite Gender: Shintarou. Tragic due to the fact that, due to how they were raised, they didn't even know their biological sex until someone outside of their family told them.
The RevealKoushi is really the strongest martial artist but he doesn't know it and it's not revealed until the last five minutes of the final episode.
Samus Is a Girl: Lampshaded in-story, when Iroha points out how ludicrous the concept of a girl being raised as a boy and involved in a Harem is after Hanzou has about an Eroge featuring said plot. Of course, meanwhile, Wholesome Crossdresser Shintarou has just accidentally kissed Harem magnet Koushi and fallen for him.
Sleep Learning: Koshi uses them to further his studies... until Momoko hits upon this as a perfect way in which to make him love her. Makes things very awkward for Iroha when she attempts a nighttime assassination.
Stripperiffic: The Uma Kamen outfit not only focuses the wearer's strength but is also the most transparent excuse for leathery horse-themed Fanservice you'll see in a long while, complete with a tail and a bit.
Super-Deformed: Momoko seemingly spends half the series two feet tall and without hands or feet.
Super Window Jump: Uma Kamen bursts through a stained glass window in an outfit FAR too small to avoid the death of a thousand razors. None of the debris even reaches the ground to harm the non-martial artists in the wedding ceremony.
Sweet Polly Oliver: Subverted in Shintarou's case, as she didn't actually know she was a girl, due to her father raising her as a boy and insisting that she was one, until the Nakajimas told her that she was one.
The Voiceless: Saigo, with Momoko able to translate because "People in love are connected by heart."
"Well Done, Son" Guy: A minor example — Koushi first wishes that his father would stop bothering him about the martial arts and just accept his dreams of being a prosecutor. It later becomes apparent that his father Unken does approve of Koushi's ambitions, only bothers Koushi to train in the martial arts because he's the target of assassins, and actually feels really guilty that Koushi has to go through all of this due to his parentage. Unken is just really bad at saying all of this.
Wholesome Crossdresser: Shintarou, who continues to present herself as a boy even after she's told that she's female.