Yongisanda(2013)

Yongisanda

Meet my neighbor - a typical fantasy novelist, more than a little scatterbrained, likes to gossip, borrow things without asking, and play MMORPGs. Oh, and by the way, he's a dragon in disguise. Named Dragon Kim.

Yeah...

(Source: Naver, translated)

Note: chapter count includes 2 prologue chapters and 1 extra