Small for his age, Yukinari has been bullied and abused by girls all his life. Now in high school, he has developed a rare condition: whenever girls touch him, or even come close, he breaks out in hives. Imagine his surprise, when he is suddenly transported to the city of Seiren on a mystic world invisibly orbiting the Earth, and populated with vast numbers of women and very few men. Fortunately, he has a new friend, Miharu-chan, whose touch inexplicably doesn't affect him.

Vampires—supernatural beings that feed on the life essence of the unsuspecting at night—have been around for centuries. However, high schooler Karin Maaka is unusual, even among her own kind. Unlike her vampire family, ever since she was a child, Karin has suffered from polycythemia: a rare disorder which causes her to periodically produce excessive amounts of blood. And the more blood she produces, the more anemic and lightheaded she gets, ultimately leading to frequent nosebleeds. Her only solution? Force her excess blood onto random strangers, which surprisingly causes these "victims" to become livelier and happier than before. With her siblings—Anju, her reserved yet affectionate younger sister, and Ren, her womanizing elder brother—helping her abilities remain a secret by altering the affected humans' memories, no one is the wiser. That is, until Karin's newly transferred classmate, Kenta Usui, finds her behavior suspicious. And to make matters even more complicated, Karin feels her blood reacting unusually to Kenta's presence.

In the future, an organization called the GGP has taken control of the world. Rin Ogata was a promising up-and-coming ballet dancer, but suffered a serious injury while dancing and decided to quit. Years later in college, she comes across a club building and soon finds herself intrigued by a transforming motorcycle-like robotic vehicle called a "Rideback". She soon finds that her unique ballet skills with balance and finesse make her a born natural on a Rideback. However, those same skills also get her into serious trouble with the government. (Source: Wikipedia)

Yusuke Urameshi is not exactly what you'd call an angel. In fact, some might call him down right devilish. But when he dies in an accident trying to save a child, he finds himself in the Spirit World. Unfortunately for Yusuke, his name is not listed in the Book of Enma, which means it was one big mistake! So he should return from the Spirit World, but must pass a few tests first, and become a detective of the spiritual world.

So now Yusuke works in the Spirit World as a half-dead, half-alive agent for Koenma, son of the ruler of the Spirit World. This position does have its disadvantages, especially when you're trying to enjoy your summer vacation and Koenma gets kidnapped! So now Yusuke must interrupt his summer fun to find Koenma and trade the Golden Seal of King Enma for his life. But if someone other then King Enma has the Golden Seal there will be chaos in the Spirit World! What's a half-dead spirit detective to do?

With the aide of his closest allies, Yusuke sets off for Magma Valley, to save the life of the one who saved his, and find out who's at the bottom of this evil conspiracy.