The 4th Grader Demon Lord is a Manga/Manhwa/Manhua in (English/Raw) language, Comedy series, english chapters have been translated and you can read them here. You are reading chapters on www.ManhwaZ.com fastest updating comic site. The Summary is
Shining black armor... A fluttering cape... and... a creaky school bag on his back!? The rumored beautiful female transfer student is a Demon King from another world!