Zynitary
Grim Fact about the world in the lower phase:
Death is Voluntary.
Yes, you've heard it right. VOLUNTARY. Not like that "You grow old and can rest anytime", no. It doesn't work like that. You need to meet the correct Grim Reaper for that. And yes, there are two types of Grim Reapers or rather, Icons of Death/Doom(or Decay).
How it works is that either you ask them to put an elderly to rest(if you are asking for a peaceful rest for your grandparents), and for that purpose, Mori(Icon of Decay/Doom) is there. Or be fatally wounded enough to fit into the category for the Icon of Death to visit and put to rest.
Random lore.