Younger Toguro

Younger Toguro is a very muscular demon who takes an interest in Yusuke Urameshi. He constantly feel emptyness within himself, which he attempts to fill with power. He originally is the teammate and lover of Genkai. They participate in Dark Tournament fifty years prior to the series, joining to kill a demon who slaughtered their disciples, and after emerging as victors, Younger Toguro wishes to become a demon. He gains the ability to manipulate his muscles depending on what percentage of power that he uses. When at 100%, he must devour the souls of those nearby to keep his almost indestructible body energized. He eventually realizes that he is looking for a stronger opponent to defeat him, which comes in the form of Yusuke. In the afterlife, he asks to be sent to the last circle of hell, which is 10,000 years of torture for 10,000 cycles until the soul ceases to exist, despite protests from Genkai and Koenma. He is voiced by Tesshō Genda in Japanese media and Dameon Clarke in the English dub.

Source: Wikipedia