Takeshi Oomura is no stranger to bad luck. Three days ago, though, his misfortunes seem to be piling up. He gets chased by dogs, seen his house burn down... and dies from a fatal concussion. "Fourteen years of life... my life was too short."
Luckily, Heaven seems to think so too: upon dying he meets an angel called Elle who immediately resurrects him. Elle explains that Takeshi's father had passed down his role to his son — essentially, Takeshi is now the holder of all the bad luck in the world, and Elle was sent to become his guardian angel. Whoop-dee-doo.
Of course, Takeshi wants to refuse, so he seizes the opportunity to pass the curse to someone else. Except his curse is going to affect an innocent little girl, so he decides to accept it himself. Elle acknowledges his acceptance and then transforms into a human, after which she explains that she has to be near Takeshi 24/7 so she can supply him with good luck. Takeshi isn't particularly happy with this arrangement.
A manga by Kenjirou Takeshita, Happy World! is a weird mix of Ecchi, Magical Girlfriend, Supernatural Horror and School Comedy. Though the tone shifts often, and it manages to incorporate some very thoughtful pieces on parenthood and life in general. There is also an OVA adaptation done by ZEXCS and KSS.
- BrotherSister Incest: The explanation Takeshi uses to explain Elle's connection to him is that she's his step-sister. Cut to Takeshi exclaiming loudly to her in a classroom "We should make a baby." And they actually go halfway through the act before realizing that they're not emotionally ready for it. As it turns out, their relationship to each other is actually more than even step-siblings...probably. Though the two were born in different ways, Takashi and Elle share a mother. Oddly, the implications are never discussed.
- Cerebus Syndrome: The first 20-odd chapters are a pretty normal for a supernatural romantic comedy. When Isra appears, though, things start getting dark REALLY fast.
- Characterization Marches On: At first, there appears to be no special significance to Isra's crown, and she's shown putting it on nonchalantly in her first appearance. Later, it turns out that the crown is a Power Limiter placed on her by her mother, and that removing it from her head is a very bad thing.
- Continuity Creep: This sets in around the same time as the Cerebus Syndrome, switching from a more episodic format to an ongoing story.
- Death Is Cheap: Elle resurrects Takeshi day in and day out. However, this constant use of her powers ends up killing her child. But luckily she's Only Mostly Dead... It turns out that the soul of the child was split between Takeshi and Elle.
- Enfant Terrible: Hikaru's little sister Michiru is a child genius who spends all of her time torturing her older sister. Not just sibling rivalry, but CIA level torture. Takeshi ends up taking her place because he can be resurrected.
- Half-Human Hybrid: Takeshi is revealed to be half-angel, and the Hoshino sisters turn out to be half-demon.
- Harsh Word Impact: A rather squicky version of this happens in chapter 10. After Takeshi and his male classmates conspire to peep on the girls during their physical exam, Elle (who's oblivious to these plans), cutely tells Takeshi that she's embarrassed about the prospect of her breasts being seen. The force of her speech bubble momentarily slices Takeshi in half, and his innards are visible.
- Have You Seen My God?: Any angel that wants to get promoted has to accept that God is currently missing in action.
- Horny Devils: Isra explains that demons draw nourishment from humans by draining their "genki". It's never explicitly stated what "genki" refers to, but it's heavily implied to be sexual energy or the like since the humans are rendered naked after being fed on and both Elle and Isra become flustered when Takeshi asks them what genki is.
- Infant Immortality: Double subverted. Elle has a one-parent child named Prayer who requires a constant flow of light energy from her to survive. When Elle uses up too much of her power to resurrect Takeshi, this ends up killing Prayer. However, Prayer's soul survives within both Elle and Takashi, allowing her to be resurrected later.
- Luke, I Am Your Father: Multiple times. As it turns out, Elle's mother was also Takeshi's mother, and the demon Isra is Elle's twin sister. Inverted with Sanae and Motoko, who are revealed to be stepmother and stepdaughter respectively.
- Made of Iron: Due to his bad luck, Takeshi is able to take a punch to the face without flinching.
- Mood Whiplash: There is nothing "Happy" about showing a smiling innocent girl, and have the next panel reveal her empty shirt now riddled with bullet holes. And then there's the part about what happened to Elle's mother...
- Not So Harmless: Isra is at first portrayed as a Starter Villain, and is driven off by Elle with relative ease. Much later, however... it turns out that she's powerful enough to bring about the end times. And nearly does.
- Tournament Arc: A demon convinces the Hikaru's father and sister to kidnap Takeshi in order to force Elle, Hikaru, Sanae and Motoko to fight in one of these to get him back.
- Triangle Relations: Elle wants Takeshi's child. Hikaru wants to marry him. When he suggests that those goals aren't mutually incompatible, they don't take it well.
- Truly Single Parent: The angels, and they can each only have one child. Usually...