|Oku forgets about characters all the time.
As for Muscle Rider:
Spoiler (mouse over to view)
He's still alive, in the last chapter he was on the alien planet with the rest of the team. Unless you mean how he originally died, which was from trying to stop Izumi during his killing spree.
Quote from purple716
Is there any manga where the male lead has an illness known as stomach ulcers.Yaoi are fine top.