I’ve been searching around and can’t find one. Some media points to Izanami, but she only died and entered the underworld.
Izanami rules over the underworld. Does it matter how she entered? She was a divine being even before her death.
The method of becoming a god of death/the underworld doesn’t seem to matter. For example, Osiris was originally an agricultural god but became the god of the underworld when he died.
How can a god die?
According to myth, Izanami died during childbirth while Osiris was killed by Set by trapping him in a box and then stabbing him (or he was carved to pieces, can’t remember)
Both, actually. The trapping in a box was an earlier version of the Osiris myth, and the dismemberment is a later version.