MC isn't exactly evil, wicked would be a better description. He sort of does what he likes without considering the consequenser, but he do have a sense of justice and cares for the people he likes.

When you begin to read this series you may think ".. hey, that dude isn't like a demon king at all!" But don't be fooled, he becomes more evil and insane throughout the story, currently I'm at the 160th chapter and really like it.
When the story begins the MC gets send to another world ,a world with swords and sorcery.
He gets reincarnated as a lowly slave of a weak magical elemental major and becomes stronger until he kills whoever offended him.
And later there is even some H action.

... Last updated on September 20th, 2016, 9:19am

MC died because of a demon practitioner in his world. MC's soul along some memories of the demon practitioner (who is died too) is transported in a body of a dead errand slave in a world of magic but he is coming from a modern world (with cultivators?) and then he begins to learn some necromancer magic and mix with some xianxia related technique. The idea about mixing magic and xianxia is good and have a high potential but the story is somehow superficial. Naming sense from the author or the translator is really bad.. solid realm, open passages realm.. and MC is a hypocrite (for me).

I had to drop it early, this novel is stupid. The title "Great Demon King" caught my attention, but the MC does not seem evil. The MC has three lives worth of knowledge, but several of his actions are moronic, like that of a 10-12 year-old. When the MC tried to "avenge" the previous owner's death, it turned into a gag with that person. First, it was not funny and second that person is a murderer. I thought he would try to kill her, but I guess not. I would not be surprised if that person turned into a love interest.