Kuro no Maou is a Manga/Manhwa/Manhua in (English/Raw) language, Seinen series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Kurono Mao is a high school student who is sensitive of his sharp eyes and bad expression. No girlfriend but gifted with friends in his own way, he had been living a peaceful life. But one day, without any reason, Kurono was attacked by a mysterious headache while in the literature clubroom and fainted. When he finally awoke....... Swords & magic, filled with monsters, an orthodox different world summoning.