The main character of this Japanese show is 14-year-old bully named Yusuke Urameshi. The series is mainly about him who - upon dying - is given the opportunity to come back to life, yet only on a condition: he has to become a Spirit Detective for the dead realm. His tasks include nabbing villians who are Yokai (or demons) and the like, but his name goal is protecting the Human Realm from the Demon Realm.

The show gets a little deeper the longer Yusuke is a Spirit Detective. He has to start entering the Demon Realm and stopping the Demon Realm from entering the Human Realm. He makes allies and learns more about his past and that he wasn't all that human to begin with... The rest of the show and all its characters have their own stories as well, but it mainly revolves around him.

Buy the anime at FUNimation.
Watch some episodes at Youtube.
Download the series at Yusuke's Pit Stop.