In Urusei Yatsura, AtaruMoroboshi considers his Accidental Marriage to Lum Invader an example of this, while the other guys at his school consider him Cursed with Awesome. A reader/viewer could swing either way; it's undeniable that, particularly in the early stories where she was supposed to be a villain until fan popularity prompted a redirection of focus, she is a Tsundere, possessive, and something of Psycho Electro (particularly her tendency to shock him as a sign of affection)... but, on the other hand, much of her angry reactions are prompted by Ataru's constant attempts to bluntly ditch her and/or chase other women, and Ataru's biggest objections are rooted in "being married to her means I can't go trying to pick up other girls"... even though Lum is beautiful, genuinely affectionate and more than willing to go to bed with him. His dreams of his own personal harem were undermined by reality: The only other girl in the series who didn't see him as a pest or a means to an end was Shinobu... who dumped him once it was clear the choice in his mind was "Lum" or "Lum and her everyone else".
Princess Hinoto of X1999 has the ability to predict the future through dreams. Her ability to predict is so powerful that she resides beneath Tokyo's Diet building and helps the politicians there determine Japan's future course. The downside is that her powers are so immense that she's permanently crippled, blind, deaf, and mute.
The cyborgs of Cyborg 009 cannot age normally. Doesn't seem so bad, but Cyborg 001 (and the most powerful one of them all, having telepathic abilities), Ivan Whiskey, is an infant, so it's highly likely that he'll spend the rest of his life never learning to walk, talk, eat solid food, and he'll never be potty trained.
Kind of subverted in a way, as if it wasn't for being turned into a cyborg he would have died.
Sesshomaru in InuYasha receives a very powerful sword born from his own demonic power. This sword has not only enormous power but also the ability to disintegrate the enemy until nothing's left. Big Bad Naraku kidnaps his companion Rin and he realizes he can't use the awesome Bakusaiga against Naraku because the virus-like effect would be too dangerous with Rin inside Naraku's enormous body. Then he discovers his brother Inuyasha being possessed by Magatsuhi. Obviously he can't use Bakusaiga to whack Inuyasha without killing his brother (like he did once with his former weapon, Tokijin). So he has to rely on his claws and Tenseiga, a sword which can only wound those not of this world (which Magatsuhi is, unfortunately defeating him's still troublesome because he uses Inuyasha's body as a shield), until Magatsuhi is defeated and Rin is safe. Also, he wouldn't be able to revive anything that's killed by Bakusaiga because his Tenseiga needs a relatively intact body to do so. Ironically, while Bakusaiga is not considered evil, and Tenseiga is "The Sword of Heaven", Tokijin - the sword that never brought him any trouble (outside of the fact that it wasn't strong enough in some cases) and was absolutely obedient to him till the day it broke - was extremely evil.
Jusenkyo, the famous Valley of Cursed Springs from Ranma ½, is capable of bestowing either Cursed with Awesome or Blessed with Suck upon those who receive its magical touch- it all depends on what spring, specifically, a person falls into. Some springs provide definite superpowers. Others, however...
Ryoga Hibiki's piglet form is small and adorable, an instant hit with any cute girl he meets. However, Ryoga is so nervous around women that this just makes him uncomfortable, and being adopted by Akane as "P-chan", when she's normally oblivious to his feelings, is like torture to him. Beyond that, he goes from a Made of Irondestructively strong martial artist into a weak and helpless animal considered delicious by man and beast alike. Couple this with the fact that he's often deep in the wilds when the curse goes off, and you can see why the pain outweighs the gain in his mind.
Wilds nothing, the first time Shampoo and Cologne see Ryoga as a pig they attempt to cook him.
Shampoo's cat form is just as small and helpless as "P-chan", though less personally risky... however, her unwilling boyfriend has issues with cats due to an ill-advised training regime he was forced into by his father, which means that the slightest splash of cold water, from any source, will send him running for the horizon.
Anime-only Villain of the Week Kin'nee is a hulking brute of a fighter, but his Spring of Drowned Priest not only makes him a skinny little weakling barely half his true size, but also messes with his mind, making him timid, cowardly, and a devout pacifist.
Ranma accidentally ate Dragon Whisker Porridge while in China. This causes his hair to grow and grow, making it a genuine and perfect cure for baldness. As Ranma already has hair, however, if he doesn't keep it under control by using another Dragon's Whisker to tie it up, his hair will keep growing until he uses it up. A lifetime's supply of hair, burnt through in about a week, tops. His self-centered father couldn't care less when he finds out, immediately trying to steal the Whisker so he can cure his own baldness.
Even more so, it's self-limiting. When he starts winning a fight using it, it gets weaker as he cheers up.
A story arc centers on Ryoga getting a special mark on his stomach that made him unbeatable in battle. Unfortunately, not only does the mark look ridiculous, but the only way to remove it was to defeat him in battle. Worse yet is that the mark shows up on his piglet form too, compromising his identity. He only got out of it by flexing his stomach muscles so the mark distorted and Ranma could defeat him.
Rouge hovers between this and Cursed with Awesome. As an Ashura, she can fly, has multiple arms, several faces, can breathe fire and hurl lightning... but, all those arms means she gets horrific backache. How bad is it? When Pantyhose Taro steals her magnetic backpain relievers, she goes on a rampage and chases him all the way from China to Japan to get them back, it hurts that much.
Another Rumiko Takahashi work, Wasted Minds from Rumic World features a main character with the useful ability of teleportation... between anywhere garbage is, be it a trashcan or landfill.
The immortals in Rumiko Takahashi's Mermaid Saga are neither indestructible nor immune to pain. In Mermaid's Scar, Mana is tied up with barbed wire by the main villain, who gleefully informs her that it's too bad there's nothing in mermaid flesh to counteract pain. At the end, Yuta informs Mana that the villain will die if the fire from the car crash he was in burns through his neck all the way. Squick.
Borderline in Neon Genesis Evangelion. Shinji Ikari always believes that his job as an Eva pilot causes him nothing but pain, but many of the characters, most notably Kensuke Aida, believe that being a pilot of an Evangelion is really amazing, and can't understand how he gets so upset about piloting. Those who do understand what's going on know otherwise.
Death Note: Light Yagami is given a supernatural artifact capable of killing anyone, anywhere, using any method physically possible, (provided he knows their name and face.) Sounds awesome. But in the first volume we are told that the Death Note is a curse to all mortals who have ever owned one. Light is not an exception. His sense of morality, once so important to him, vanishes within days of receiving the Death Note, he has to take part in the killing of his own father who was once the man Light admired above all others, and oh, yeah, he gets the crap shot out of him.
Interestingly, a straighter example of this trope is given by the false rules. If you don't write any name in the Death Note 13 days after you already wrote one, you die. If the Death Note is burned or destroyed, all who have touched it will die.
There's more. Misa is one of the people who didn't get a happy ending, probably because of the Death Note. She died without anyone to love her on Valentine's Day, after giving up her lifespan for a pair of eyes only to be used by the person she loved. Also, Mikami dies knowing that he failed his "God". Anyone who uses the Death Note seems to have what they value most taken away from them - for Light, that was his morality; for Misa, that was someone to love and someone who could love her back; for Mikami, that was approval from "God"/Kira. No matter who uses the Death Note, they will never be truly able to achieve happiness. It's a terrible curse that comes with the power to kill.
Subverted in Ah! My Goddess: Keiichi Morisato is granted a wish by a goddess, which promptly gets him kicked out of his dorm, and leaves him with said goddess and her sisters as dependents and being harassed by everyone except the goddess and his sister. Despite all this, he is still happy with his wish, and makes this clear at several points.
Ichigo initially felt his ability to see (but not be able to help) ghosts was this, especially as he felt it contributed to the death of his mother when he was nine years old. Once he obtained shinigami powers, he felt he was Cursed with Awesome instead. This is only resolved after he's Brought Down to Badass whereupon he accepts his power as a part of himself.
Hollowfication provides a vast boost to a shinigami's normal power by giving them hollow power as well. The price of this for the Vaizards was exile under threat of execution and an inner monster they had to fight to control. They eventually come to accept their new powers and are eventually reconciled with the society that had once cast them out.
Soi Fon feels this way about her bankai, as her fighting style relies either on killing the foe in two precise hits, or just beating the crap out of them at high speed (shunko), then she gets a giant missile, which she has to take the time to anchor herself in order to fire, and can only fire it once in a while or she won't have the energy for the missile to really work.
Several people in Mushishi appear to be genuinely blessed after being infected with mushi that gives them special powers (prophetic dreams, the ability to see while blind, etc.) Unfortunately, mushi has a nasty tendency to grow in power and get beyond its user's control, which usually results in disaster for the infected individual and the people around them.
Russia from Axis Powers Hetalia hates General Winter for tormenting him with the constant cold. However, in war time, the weather is effective on his enemies.
Yami No Matsuei has sixteen-year-old Hisoka Kurosaki, who has powerful empathy which is helpful in his line of work as a shinigami and allows him to feel emotions, see memories, and pick up imprints of clairvoyance off inanimate objects. His power also keeps him from physical contact with most people, brings him large amounts of both mental and physical pain and was the reason his parents despised his very existence and locked him in a cell for most of his life up until he was raped and murdered by a psychotic doctor.
Practically every Geass power granted in Code Geass starts off sounding pretty cool... until it becomes uncontrollable and makes its user's life hell (unless it already had a terrible drawback to begin with). Examples:
Mao can read the thoughts of anyone within 500 meters. To be more precise, Mao reads the thoughts of everyone in 500 meters. This was bad enough when he could turn it on and off. Once it becomes permanently active, he has to read the thoughts of everyone within 500 meters. Unlike Lelouch, there's no easy way to fix the problem, isolating him and eventually driving him insane from being bombarded by random thoughts. He's obviously in so much pain, in fact, that it's hard to see how his power was ever a blessing in the first place!
Rolo has the power to stop perception of time. However, his heart stops along with everything else, putting the time limit at a few seconds and making it risky to use in quick succession. This is what eventually kills him, when he consciously overuses his Geass to save Lelouch.
Pre-immortality C.C. had a Geass which acted as a love-magnet, which was nice until she couldn't turn it off and people got increasingly obsessed with pleasing her. This made it impossible to tell where people's true feelings ended and the Geass-generated love-brainwashing began, causing C.C. to become jaded and cynical about love.
Suzaku may not have a Geass, but he does get a command from Lelouch to "live", forcing Suzaku to survive by whatever means necessary. For a Death Seeker like Suzaku, this is bad enough as it is. But it goes From Bad to Worse. Thanks to the "Live" Geass, he ends up nuking Tokyo and causing thirty-five million deaths when using the nuke was the only thing left to keep Kallen from killing him. Then it becomes Cursed with Awesome as he turns the command into a quasi-SEED mode. In the Grand Finale... well, let's say that he was given a Fate Worse than Death. God, it sucks to be Suzaku!
Lelouch's mother, Marianne, is also a case. Her Geass apparently never activates... until she's shot to death, locking her in the body of a young girl she was training... and on time share to boot. However, she mentions that she could have gone back at some point if she had wanted.
Elite Mook and Knight Of One, Bismarck Waldstien, has the power to see the future. It's permanently active, so that eye, while still usable, sees the future constantly. He has it clamped shut with some easy to remove clips.
All this gets a lampshade courtesy of Jun Fukuyama in one audio commentary, where he observes that most Geass powers would be nice to have once in a while, but they become terrible curses when permanent.
Fridge horror: If Rolo were to lose control of his Geass, everyone near him would be frozen forever... Except for the fact that his heart would stop from that point anyway, so he'd survive a minute, tops. Maybe going for a Heroic Sacrifice was the best option he could have hoped for.
Kurau in Kurau Phantom Memory benefits greatly from her Rynax-powers in her job as an agent, but it causes her some trouble too. She gets separated from her father at a young age and goes through years of loneliness, because she has to hide her powers and the Rynax she merged with has to miss its "pair". Once her pair appears, she has to run from the authorities, while being more vulnerable as she has to defend her "little sister" as well. Still, flying, being able to phase through walls and disintegrate massive objects is pretty cool.
Gene and Jim of Outlaw Star inherit one of the most advanced ships in the galaxy after one of their clients kicks the bucket. This would seem like a good thing, until the two realize that it's going to cost them an arm and a leg to dock, maintain, and arm the damn thing. It effectively paints a big fat target on Gene's head for the Kei pirates to strike at. Gene puts it best when he says, "We sure inherited a big pain in the ass."
The titular heroines from Gunslinger Girl get saved from death and gain enormous strength and agility through cybernetic implants. Alas, this comes with severe mental conditioning (including enormous emotional dependence on their "Handlers") and an immensely shortened lifespan, so the girls will likely die before reaching adulthood.
In The Law of Ueki, kids are granted powers by candidates gunning for the position of God, who must then fight in a tournament. One power in particular seems unbeatable (The power to turn ideals in to reality), until you find out that it takes away a year of your life to use it. An even worse example is the kid who can turn his forehead into a diamond, but only when his hands are in his pockets. This trope is the focus of the series.
Ueki Kosuke, who has the power to turn trash into trees. Although he does find some extremely interesting and practical uses for this power in battle, he is helpless without any rubbish.
That is, until it turns out that he can use a piece of tree to create another tree.
Also, the piece of trash has to be small enough to fit completely inside one or both hands.
I think the ultimate reveal is his level-2 power. While other powers revolve around changing one object to another, Ueki's power allows him to infinitely transform tree parts (trash) into trees, which influences his level-2 power of reversing the objects his opponents have changed, returning them to their original state. More interesting is that his candidate, Kobasen suggests that he deliberately chose his power knowing that it'd eventually have a high pay off. Despite the fact that in it's initial state it's not a bad power, it's just not as cool as the others.
Seiichiro Sano, who can turn his towels into iron, but only as long as he can hold his breath.
Ai Mori, who can later on make her opponent really, really love glasses. The effect is immensely powerful, but before it can be activated the opponent must strike a rather specific girly "Squeee!" pose, making the power practically useless.
Robert Haydn, who has the aforementioned power of making ideal objects (for example, a cup that will never spill a drop even if turned upside-down) at the cost of one year of his lifespan.
Marco Maldini, who can change tomatoes into magma. I'm sure by now you get the point.
If any of them hit a non-powered person with their power they lose one of their innate talents, and losing all your talents causes you to be struck out of existence. Welcome to the suck.
If they win a fight with another empowered kid, they permanently acquire one of their opponent's innate talents as their prize, which is the main motivation for the kids to fight each other. Sounds like a good deal, but the talent they get is completely random- the talent you could get from that difficult battle you just won might be your opponent's talent for judo or understanding math, which would be extremely useful... Or you could get their talent for memorizing song lyrics or doing the moonwalk, which are pretty useless.
Law of Ueki Plus, sequel to the above series brings back Kosuke, having lost all his cool heavenly powerups and his original powers. He's sent to a new world full of naturally born power users and is forced to choose a new power to survive. By chance he accidentally picks the power to wield a mop. Things get more interesting when he learns how to make it grab stuff and hit people with it's end. In the end turns out that the mop is actually a powerup that allows Ueki's new friend to reach it's final form
Though quite a few of these are more Cursed with Awesome; They start off sounding like a curse, but turn out to be amazing. Such as Ueki's, for example. Kind of a mix here, though, I suppose.
Yakumo of School Rumble is an empath who hears the thoughts regarding her from any guy who has any interest in her. Her being a Yamato Nadeshiko, that usually means all guys — it comes as a surprise when she can't hear anything from the male lead (because he's purely in love with someone else, her older sister) — and people don't help her because she looks too perfect to need it. The blaring thoughts of the Stalker with a Crush don't help her situation, either.
Zelgadis Graywords from The Slayers wants to become strong, so his great-grandfather makes him strong. By turning him into a 1/3 rock golem, 1/3 blow demon chimera with blue skin and wire hair. He then devotes his life to finding a cure for this condition.
Most of the time we see him he's hanging around the rest of the cast or has himself covered in clothes head to foot. Also showing the effects of his appearance beyond it being funny is not particularly on the show's agenda. There's also been rumored a solo story about Zelgadis on his own that got scrapped because it was too dark and serious for the usual Slayers tone. But put in some imagination (given how most people react to someone who looks weird) and the fact he sinks in water, his hair can get stuck in wood etc and there's plenty there that sucks.
In the new series, Slayers Evolution-R it's shown in a flashback how children Zelgadis used to play with start to consider him a monster after his change - oddly, considering that they also used to play with wolfman Dilgear and fishman Noonsa with no reaction to their monstrous appearances. It seems that Zelgadis only became serious about finding the cure after it became clear to him that Rezo was only using him as a tool, and didn't change him because he cared about him, as he claimed.
The five Signers of Yu-Gi-Oh! 5Ds consider their power to range from a mere inconvenience to a dire curse.
Wangan Midnight has the Devil Z, a heavily tuned Nissan Fairlady Z (S30, which was sold as the Datsun 240Z in North America). For a car from the 1970s, you'll be amazed at how fast this badass mother can go. The trade-off? It's extremely hard to control, and thus has a long history of accidents involving the deaths of its past owners. In fact, it's believed to be possessed; one chapter has the protagonist Akio exclaiming that his foot is stuck on the pedal as if it was being pushed down.
Chise in Saikano is turned into the ultimate weapon, which makes her invincible and she becomes absurdly strong as well. Comes at a very steep price: Using her powers hurts her directly, and is slowly taking away her humanity. Oh, and she can't control her powers very well, leading to her destroying several cities.
A Certain Magical Index: Touma has what he calls "Imagine Breaker", a right hand that can absolutely cancel any esper/magic power it touches (even, according to him, miracles from the gods), which is useful considering the extremely powerful trouble he attracts starting with the first episode. However, it doesn't protect the rest of his body, isn't of any use in mundane situations, interferes with beneficial powers (e.g. healing), can't be turned off, and also cancels his luck, making every day a bad day and probably causing most of the deadly trouble in the first place. Without an inhumanly-skilled doctor on hand, he'd likely have died several times over by now—he's actually ecstatic when he survives an arc without getting sent to the hospital for heavy injuries.
In Fruits Basket, the few perks that come with being possessed by the Zodiac spirits don't turn out to be all that helpful. Although it is occasionally helpful to turn into an animal, it's generally outweighed by the number of times you transform when you don't want to.
Hatori gets an especially bad case. You'd think that at least being the dragon would have some great perks, but nope! His ability to talk to dragons, which would be amazing in any other fantasy setting, is completely useless because there aren't any dragons in modern Japan. And rather than transforming into your typical Eastern dragon, he turns into a seahorse - a "baby dragon". He gets teased mercilessly for it.
Ixpellia from StrikerS Sound Stage X of Magical Girl Lyrical Nanoha has the ability to cause the Mariages to arise, whereupon they would immediately sally forth into battle. Great when you have to fight in a war. Not so great when you neither need nor want to fight anymore and your undead warriors with one track minds won't stop no matter how much you beg them to.
Nishijou Takumi the real one from Chaos;Head awakened unparalleled Gigalomaniac powers at age 10, which allow him to alter reality to match his thoughts. However, using his powers also gives him progeria (rapid aging); the more power he uses the older and sicker he gets, and he can't use his powers to fix the problem. When the series opens, the real Takumi is close to death, having used a great deal of power to create the protagonist.
In Chrono Crusade, it's implied that all of the Apostles have side-effects that go along with their holy powers. For Joshua, he has the ability to heal, but along with it comes an Incurable Cough of Death and seizures, which his powers can't heal. Azmaria also has the ability to heal others, but she believes it brings misfortune since many of the people she was close to in the past died, often because of people wanting to use her powers. Mary Magdalene can see the future (and various other things), but she's seen so many visions of other people's lives that she's lost her own memories in the shuffle. The anime also has Rosette, who is blessed with stigmata, but that only brings her constant pain, makes her a target for Aion to brainwash and control, and she later ends up using her powers to wound Chrono, which kills him in the end.
Dragon Ball Z. In the movie Bardock, Father of Goku, Bardock is "blessed" with the gift of prophecy by the natives of his most recently conquered planet. Not because the alien felt it would help, but because he wanted Bardock to feel the same helplessness in the face of his own species' demise. Sure enough, the only vision he gets is of Frieza destroying Planet Vegeta, and nobody will believe him. Do not tick off psychic aliens. It's not all bad, though: he also gets to see that his son will grow up to be a good warrior, and will fight Frieza one day...
The pactio cards in Mahou Sensei Negima! (not to be confused with Negima!) have suck written all over them. When the pactio is activated it randomly triggers one of three cards - the null card, the cosplay card or the armour card. The armour card is for maximum offense, the cosplay card is a powerup but it isn't as strong and the null card turns the recipient into a chibi animal which can't actually fight. So that's a 1 in 3 chance of being useless in a fight. To top it off, regardless of which card is activated, when it wears off (after a very short time) the person is both tired and very hungry. So if it runs out before the fight is over you are in even more trouble.
In the original manga, Chisame kinda got shafted in the Pactio department. Her artifact, a Magical Girl staff that gives her super hacking powers, is theoretically incredibly useful...except that it requires electronics to function, and the next arc features the cast getting Trapped in Another World, where there aren't any electronic computers, rendering her artifact more or less useless. Apparently, it also works well on magical computer, as Kurt Godel's tech can attest.
Not to mention that before they leave for the magic world, Chisame was bored because she had already used her pactio artifact to become the Queen of the Internet.
In Soul Eater, Crona's blood is a sentient being named Ragnarok which offers very strong capabilities in offense, defense, and manoeuvrability. He does this by hardening to stop attacks or turning into a sword, needles, or wings. Unfortunately, the process of getting said powers as a child was stressful enough that Crona is hardly ever in a state of mind that isn't depression or insanity. Also, Ragnarok likes to bully Crona constantly and, being initially huge and musclebound, is able to easily overpower his partner. Factor in the fact that Ragnarok appears by violently and painfully ripping out of Crona's back and you have a very undesirable (but still fun to watch) power.
Gaara from Naruto had sand-related powers given to him at birth which, by automatically blocking any attacks, make him virtually unkillable. Unfortunately, this power has also made everyone around him want him dead. He was deprived of any sort of love as a child, which brought him great depression. Once, he even tried to slit his wrist in an attempt to commit suicide.
In fact not just Gaara, though he is the most blatant example: Jinchuriki in general get enormous chakra reserves, access to a super powered mode and extra powers related to their Biju. But they're seen as a ticking time-bomb at best, and if they use their super-powered mode they could lose control, which can release the beast inside them, which kills them and only makes their reputation worse. And even if they live their whole lives without an accident, their home village will still remove the Biju, killing them, and reseal it in another kid, continuing the cycle.
In Puella Magi Madoka Magica, being a magical girl sounds great! Not only do they get superpowers, they get a wish for anything they want when they become a magical girl. Sure, they have to fight Witches, but that's par for the course. Except there are a few things Kyubey neglected to mention, like that their souls have been removed from their bodies and placed in their very appropriately named Soul Gems, so magical girls are basically liches. Furthermore, magical girls will eventually turn into Witches when they reach their Despair Event Horizon, and they will. There's also the fact that the wishes the girls make typically don't make them happy for long, backfiring horribly or turning out to not be what the wisher really wanted - though that doesn't seem to be something Kyubey has control over.
In Tantei Gakuen Q, Megu has photographic memory, which aids the team immensely. On the other hand, if she sees a particularly gruesome crime scene, she'll keep that sight in her memory for the rest of her life. Her teacher has kept her away from crime scenes just to avoid traumatising her for life.
Urabe, the mysterious girlfriend of Mysterious Girlfriend X, has some pretty amazing psychic powers... which work exclusively through saliva-drinking. She can drink someone else's or someone else can drink hers, but spit has to be involved. (That's right, folks, she's blessed with suck-based powers...) As a result, this trope applies equally well to the manga/show itself — its unique and clever concept is the same thing that keeps many potential readers/viewers away.
Giorno in Part 5 can actually inflict this on his enemies. By hitting them with Gold Experience, transfers life energy to them and causes them to perceive time much more slowly as their mind races as supersonic speeds. Unfortunately, their body don't go any faster, which just causes them to become disoriented, especially when Giorno then punches them in the face and they get to feel every agonizing millisecond of it.
The Ashikabi from Sekirei, who are blessed with a Magical Girlfriend via a Magic Contract Romance. Unfortunately, There Can Be Only One and all Sekirei are required to battle to the death until only one of them remains. That means out of 108 Sekirei and 80+ Ashikabi, only one of each gets to have a happy ending.....while all the rest will have to watch their soulmates die in battle.
Anri Sonohara from Durarara!! is the not-so-proud owner of an ancient, unnatural sword that makes her a fearsome warrior, with superhuman strength, speed, and combat abilities, as well as the extremely useful power of taking over the mind of anyone she's ever cut with it (and anyone they cut in turn, essentially turning her into the Hive Queen). The only reason she's able to control the sword's power? Her childhood was so mind-bogglingly traumatic (it'd be easier to count the adults in her life who didn't somehow abuse her) that her personality is almost completely disassociated from her mind, and she literally cannot fathom the sensation of love. (the demonic sword is driven by a twisted form of "love", expressed by killing humans, since being a sword that's the only form of affection it knows). And should she ever get over her trauma or learn to feel love again? She'll turn into an extremely dangerous serial killer.
Shizuo Heiwajima grew up with Super Strength but not the necessary invulnerability to properly utilize it, causing him to have a childhood filled with broken bones until he built up the necessary resilience. He also has a severerage disorder, in which nearly anything can piss him off (most of all Izaya), causing his predilection to violence and getting him fired from several jobs when he was older. The incredible irony in all this is that Shizuo hates violence, the hypocrisy of this being fully aware to him, which has shot his self-esteem straight to hell.
Takeru, whose powers involve Playing with Fire. In return, his ability heats up his own body, meaning that overusing his powers could burn and kill him, if his body weren't smart enough to shut his power off for him.
Fujimaru, whose powers would directly attack his brain if he didn't wear a Power Limiter, resulting in a case of I'm Having Soul Pains. Furthermore, the strain could kill him within a few hours.
Shirayuki has Complete Immortality... except she's kept locked up, and combined with her ability to constantly regenerate and mass-produce the source of everyone's powers, she's forced to watch as her abilities are used to ruin everyone's lives, knowing that this might never end.
In Read or Die, being a Paper Master is a pretty sweet deal, if you're inventive enough. The downside? Biblophilia on a massive scale. A love of books and reading that progresses beyond "love" into "life-destroying obsession". The protagonists of both the original OA Vs and the TV series adaptation are shown as being so crazy about books they can hardly live normal lives; beyond making themselves unemployable because they are constantly forgetting about their tasks, or even showing up at work, for the sake of reading, they drive themselves bankrupt in pursuit of more books to add to their personal libraries and even endanger their health through a combination of spending money that should be used for clothing, bills, food, etcetera on yet more books and getting so caught up in reading that they forget to eat, sleep and bathe.