A prequel to the original series, the story centers on Chiffon Fairchild's first year at West Genetics prior to her becoming Student Council President, and also explains the origin of her title, "The Unmatched Smiling Monster".
(Source: Wikipedia)

A powerful sorceress, Feicia Rand Philistin, once tried to conquer the nation of Shurian. In her wake of terror and destruction, a man stood up and rebelled against her oppression and domination. The people called him Maian the Brave (Yongja Maian) and it was he that sealed the evil sorceress.
A thousand years later, Fenix Maian in the biggest mistake of his life releases the sealed sorceress that his ancestors have tried so hard to keep imprisoned.Now he has to keep the sorceress from taking over the world once again...
(Source: SolitaryCross)

The Freezing Pair Love Stories manga tells the story of how the various Pandoras and Limiters met.
(Source: ANN)

Weak, bullied, and pessimistic about life, that's Setsuna Kashiwagi. On the verge of jumping off a bridge, a mysterious man appears behind him and offers the contract "10 million yen in exchange for your life in a year." Skeptical at first, he accepts. Waking up the next morning, thinking it was just a dream, he notices 2 beautiful women sitting beside him. They are Kanna and Rena, Oni princesses here to claim his heart in a year.

Gi Yuh is the leader of the strongest gang in his high school. He lives together with his younger sister, who seems to love him.
When saving the beautiful Ha Na from a truck he instead gets injured and lies in coma for two weeks. During these two weeks he dives into a strange dreamworld and after his recovery he is not the same anymore. He regularly dreams about what seems to be a past him. To find out what happened to him he asked his teacher for help, who has friends, who deal with fortunetelling and supernatural powers. Here he finds the answer to his strange condition: He is supposed to be a "higher" ghost", who takes the position of a dead or soon-dying person.
(Source: MU)