When Professor Akira Todou [[ThroughHisStomach steals his lunch box]], Yuuhi, a hot-headed but [[DefrostingIceQueen cold-hearted]] student, unwisely punches him. He assumes Todou is taking him to the police, but instead Todou suspiciously drags him to his house. To Yuuhi's surprise, he demands Yuuhi become his housekeeper and nanny to his son [[CheerfulChild Shouta]]--a job Yuuhi quickly [[ChildrenRaiseYou comes to love]]. After some drunken fumbling Yuuhi is startled to realize his feelings for Todou, while Todou assumes he's upset and tells him it was an accident. This being the opposite of what Yuuhi wants to hear, he disappears for awhile, ignoring all of Todou's [[DiggingHimselfDeeper pleas to forget it]]. Eventually Shouta runs off to Yuuhi's place and Todou seizes the opportunity to sort things out. They [[RelationshipUpgrade get together]] to Shouta's [[HasTwoMommies great delight]].

Another obstacle arises with the appearance of Todou's younger brother, Kazuki, who is obnoxious, [[ArmouredClosetGay homophobic]], and determined not to leave until Todou agrees to an ArrangedMarriage. After both brothers go too far when Kazuki molests Yuuhi, Todou leaves to give Yuuhi space and to confront his father about the marriage--which turns out to be for Kazuki rather than himself. In the meantime Yuuhi, who thinks things are over with Todou, and Kazuki, who thinks Yuuhi is apathetic about it, end up coming to blows. Yuuhi gets [[DivingSave knocked out]] in attempt to [[PapaWolf protect Shouta]] when he runs between them, an action which helps change Kazuki's mind about [[GayAesop homosexuals]]. Having rushed to the hospital, Todou responds to Yuuhi's pessimism by proposing and reveals that their separation was in part so he could arrange to get Yuuhi put on his family register. Yuuhi, of course, accepts and they all live HappilyEverAfter.[[note]]until Fujisaki decides to do a sequel anyways[[/note]]

''HappyYarouWedding'' is Creator/FujisakiKou's first serial manga, and the beginning of a much larger series that follows those connected to the Todou Group[[note]]the company of Akira and Kazuki's father[[/note]]. The series' chronology is: 1) ''Manga/HappyYarouWedding'', 2) ''Manga/UtsukushikiKemonotachi'', 3) ''Manga/VirginLove'', 4) ''Manga/TorikoNiNattaKemono'', 5) ''Manga/JunaiNoSeinen'', 6) ''Manga/KemonoWaAiDeIyasareru'', 7) ''Manga/PlayboyAmour'', 8) ''Manga/OboreruKemonoNoKoibito'', 9) ''Manga/MensLove'', 10) ''Manga/{{Aikata}}'', and 11) ''Manga/UetaAikata''. 11 volumes and counting.

!!''Happy Yarou Wedding'' provides examples of:

* ArmouredClosetGay: Yuuhi suspects that Kazuki's vitriol is just a cover for his {{gayngst}}, especially after he meets {{C|losetKey}}hiharu. He's right.
* ArrangedMarriage: Kazuki shows up at the doorstep claiming he's there to drop off marriage candidate portfolios for Akira. When Akira confronts his father about trying to arrange a marriage for him his father replies that he knows better than to try to interfere with his life and that the candidates were actually arranged by Chiharu for Kazuki.
* BigEater: Shouta. Yuuhi gets quite flustered when Kazuki points out how chubby Shouta is because of his cooking.
* BigYes: We get several combined with a HappyDance from Shouta when he thinks Yuuhi's going to become his mama, and again when he learns Yuuhi will move in.
* CheerfulChild: Shouta.
* ChildrenRaiseYou: {{Downplayed|Trope}}. Taking care of Shouta definitely spurs on Yuuhi's emotional growth, but Todou's influence, both as a lover and a quasi-father figure, plays an equal role.
* CrazyJealousGuy: Todou from time to time.
* CrouchingMoronHiddenBadass: Akira is generally a goofy DirtyOldMan with occasional CrazyJealousGuy moments, but the reason his father gave up interfering with him at all is because he firmly believes Akira would try to either kill or utterly ruin him and his company if he did.
* DiggingYourselfDeeper: After a slightly drunken makeout session is suddenly halted by Yuuhi, Todou fears he's made him uncomfortable and lies that he mistook him for his dead wife. Since Yuuhi had stopped because he was shocked to realize he was in love with Todou, this crushes him and he decides to never return. Todou continues to text him with messages like "I have no interest in men" and "sorry for making you feel bad" in attempt to get him to come back, but of course this just makes Yuuhi more miserable.
* DirtyOldMan: Yuuhi suspects Todou is going to rape him when he first brings him to his house. His prediction turns out to be wrong, but he's still a DirtyOldMan anyways.
* DivingSave: Yuuhi happens to hit Kazuki's BerserkButton at the same time as Shouta tries to interfere in their fist fight. Yuuhi ends up diving to protect Shouta and gets a harsh blow to the head for it.
* GenderMisdirection: Todou refers to Chiharu, Kazuki's tutor, as being a "substitute mother" to Kazuki. Yuuhi assumes he's a woman because of this ambiguity, but he ends up being a man.
* [[HasTwoMommies Has Two Daddies]]: Shouta is delighted to have "Yuuhi-mama" become part of the family. Yuuhi is less than keen on the name.
* HouseHusband: Yuuhi, eventually.
* ImagineSpot: When he first meets Todou, he's so certain he going to being forced into sex that when Shouta shows up and starts asking for omlette rice he starts speculating about "omlette rice play" and whether they're having a threesome ([[{{Squick}} with a 5 year old]]).
* {{Jerkass}}: Kazuki is none too nice to Yuuhi. On the flip side he's a good uncle to Shouta which is why Yuuhi tolerates him at all.
* LadykillerInLove: Former "King of the Night" Akira Todou.
* LastNameBasis: Yuuhi never makes the switch from Todou to Akira, even when he becomes a part of the family.
* LazyHusband: Todou, especially in the last chapter. Yuuhi outright states that even Kazuki is more useful than him.
* MakingLoveInAllTheWrongPlaces: "Making love at all the wrong times" is more apt considering they have an energetic five year old to worry about, but they aren't always good at keeping it in the bedroom either.
* MenCantKeepHouse: When he first starts working for Akira, he describes the house as "the tragedy of a single man". Subverted by Yuuhi himself.
* MissingMom: Like Shouta, Yuuhi grew up without a mother and had a very lonely childhood, hence why he's so determined to be the perfect parent to Shouta.
* NotIfTheyEnjoyedItRationalization: Kazuki is determined that two men can't have a real relationship and considers Yuuhi's reaction to being molested by him as proof. Later in the series it become clear why this is such an issue for him.
* OperationJealousy: Yuuhi pulls a bit of one when he lies about him dating his best friend.
* PapaWolf: Yuuhi is very much one. Because his own childhood was so lonely he wants to give Shouta the best childhood he can and is fiercely protective over him.
* PrimalScene: Yuuhi keeps trying to cover these up as "wrestling" but Shouta doesn't entirely buy it.
--> "Why do you need to take your pants off every time?"
* ReallyGetsAround: Todou used to. Yuuhi's implied to have a pretty long string of girlfriends as well, who he dated simply because they asked.
* SugarAndIcePersonality: Yuuhi, who was considered to be really cold-hearted by his girlfriends but was really just afraid of letting people in. The more time he spends with Todou and Shouta, the more the dere side comes through.
* TaughtByExperience: Kazuki thinks he could wipe the floor with Yuuhi, but Yuuhi is quick to point out that he's never been in a real fistfight before. Yuuhi may not be trained in martial arts, but his experience gives him the edge over Kazuki.
* ThroughHisStomach: Akira steals Yuuhi's bento and then is convinced he must have him as his housekeeper.