Galaxy Express 999 Season 4 Episode 11 The Planet of Funeral in the Mist

The Foggy Funeral Planet is a planet where, as all its inhabitants have become cyborgs, everyone is immortal and they think not much of death. They've begun to practice performing funerals for whoever they feel like and they make a pastime of it. Maetel and Tetsuro are attacked and buried alive but are rescued by a woman named Machiru. She tells them why the planet has become the way it has, but then she is sacrificed for a funeral herself!