Yu Yu Hakusho 2x27

Fifty years ago, Genkai and Toguro were actually teammates who fought and won their own Dark Tournament, before becoming violently estranged. Yusuke Urameshi arrived just in time to see his teacher slain, and assaulted Toguro in a rage, only to be knocked away by one devastating blow. With the final round of the tournament soon to begin against Toguro, Yusuke must find a way to keep that from happening again.