After 5 minutes of being Critical, after receiving a Killing Blow, or after Poison or Disease have run their course, a character will die. Upon death, a character’s “soul” will remain with their body for 5 minutes. After this final time period, their soul “moves on.”
At this point, the player must leave a “Blood Mark” (a long strip of red cloth that represents a dead body, with their character name written clearly on it) where they died, along with any in-game items on their person. After this, they must go out of play and find a plot member.
Do note that even death can be overcome, and that this state is not necessarily permanent. Do also note, however, that characters cannot come back from the dead more than a handful of times before truly passing on.