here's a summary if you do not know
Kurosaki Ichigo is a 15 year old boy that has an ability to see ghosts/spirits. Because of his ability, he is able to meet a female death god (a.k.a Shinigami) named Kuchiki Rukia. To save his family and friends from unwanted soul-eating spirits (Hollows), Rukia transfers her Shinigami powers to Ichigo. As Rukia takes on a human shell, together they solve mysteries involving spirits and hollows until from the spirit world comes 2 other shinigamis explaining that it is illegal to transfer Shinigami powers to humans and Rukia exceeded the time limit to stay in the human world. After they sentence her death for breaking the laws, Ichigo snaps and swears to everyone he will retrieve Rukia by breaking into the spirit world.
Source(s):
http://thebigtv.net
http://animenewsnetwork.com
http://wikipedia.com