The main protagonist of the manga and anime series YuYu Hakusho.

He is a Spirit Detective who is tasked with protecting the Human World from various supernatural threats over the course of the series and his closest friends, as well as greatest allies, include Kuwabara, Kurama, Hiei, Keiko, Genkai, Koenma and Botan. He is also the de facto leader of Team Urameshi and the general person to look to when the going gets tough.

At the start of the series, Yusuke is an uncontrollable teenage delinquent/street fighter with little to no positive qualities to his character. Over the course of the series, he starts becoming a better person, changing into an almost altruistic defender of the Human World while he himself continues to become a powerful martial artist.

(Source: Yu Yu Hakusho Wiki)