Hunter x Hunter

Twelve-year-old Gon Freecss one day discovers that the father he had always been told was dead was alive and well. His Father, Ging, is a Hunter—a member of society's elite with a license to go anywhere or do almost anything. Gon, determined to follow in his father's footsteps, decides to take the Hunter Examination and eventually find his father to prove himself as a Hunter in his own right. But on the way, he learns that there is more to becoming a Hunter than previously thought, and the challenges that he must face are considered the toughest in the world.

Synopsis from Anime News Network