Shinigami death spirits are sometimes portrayed as spirits that lead the dead into the afterlife or --in a more sinister turn -- convince people to die, especially by their own hand. Buddhist Spirit Mara, whose roots go back to India, is sometimes called a 'shinigami' as it is a spirit of death and is often classified as a demon, not a God.
Shinigami turn up in some classical Japanese literature -- generally in a negative context -- but have really come into their own, ironically, in modern times. And why not? They are a delicious addition to a story and precisely because they don't have a folk-heavy past, we writers can take Shinigami and make them our own.
In my novel Cruel and Unusual Magic, a young Shinigami, Kai Sugi, joins Soul Eater Julian Lake on his adventures at the Lake of the Dead in Aomori Prefecture in Japan's far north. Kai has the power to absorb the souls of the dead and send them on, though he never explains exactly where 'on' leads to. A good place or a bad place? In the book, he was left with a human family as a baby and began to come into his powers in his teens. I plan on developing his story when I continue Julian Lake's adventures in Japan in a follow-up to Cruel and Unusual Magic.
Death Note, Japanese movie. Death Note, Japanese animation.