I became the first demon Lord in another world with my skill

Kurayami Saito got reincarnated in another world, where sword and magic exist.

But the only problem is monsters don't exist in this world.

But which his skill he became its first demon Lord.

Ps: hello I am the author this is a warning.

My first language is not English, so the grammar of this novel is not that good but if you see any wrong sentence in the novel I tried to improve it to the next chapter.

So without future ado pls enjoy my novel.