Hokuto no Ken Episode 57
Away from his friends and family, Rei thinks about what has happened in his life. How he met the likes of Kenshiro, Mamiya and Toki. His body then begins to rupture.
Having said he had no regrets, Rei dies. Some of his blood trickles out of the house, where everyone sees it. They realise Rei is dead.
Kenshiro says that they will never forget Rei, as he burns the house down. Mamiya happens to see the big dipper in the sky, but she can no longer see the star of death! Lin says Rei's death has caused a miracle for her. Farewell, Rei.
In the manga...
-In the manga, Rei dies seconds after entering the house. The anime adds all of those flashback scenes.
-The preview segment for this episode had a naked, swimming Mamiya in it. This is not actually in the episode, though (I looked real hard).