Now I'm a Demon Lord! Happily Ever After with Monster Girls in My Dungeon

is a light novel and manga series written by Ryuyu (流優), illustrated by Dabu Ryu (だぶ竜; light novel and manga character design) &amp; Tōno Nōto (遠野 ノオト; manga only), and licensed by Kadokawa Shoten that debuted in November 10, 2017. The manga adaptation was serialized in Dra-Dra-Dragon Age from May 4, 2018 to December 7, 2018, serialized in Dra Dra Sharp# afterwards to September 3, 2020, and then Dra Dra Flat♭ from then onward.

Plot
One day, I woke up only find out that I’d become a Demon Lord, an individual responsible for protecting a dungeon. The world I’d been spirited away to was one filled with violence. Gigantic monsters wandered through it and competed with each other each and every day for the right to survive. I had no choice but to strengthen my dungeon’s defenses in hopes of living another day—or at least that was what I’d thought. For some odd reason, I instead ended up spending my days in relaxation and bliss.

This is Yuki’s story, my story. It tells the tale of how I spent my days after settling down in a dungeon with a self indulgent, “supreme” dragon girl and a young vampire.

Official

 * Official 'English light novel webpage
 * Official light novel webpage (in Japanese)
 * Official Dra Dra Dragon Age manga webpage (in Japanese)

Other Sources

 * Light novel


 * Manga