I'm Mortal is a Manga/Manhwa/Manhua in english language, Webtoon series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Morty is a reaper, but he wishes to befriend a human. It's not easy, since most humans see him as an intimidating skeleton, which makes it hard to start any friendship at all. However, one day Morty meets Lance who not only sees him as a regular person, but also believes that Morty is just a regular guy. Scared that Lance may reject him once he knows the truth, Morty decides to pretend to be a mortal himself.