Okinodoku desu ga, Bouken no Sho wa Maou no Mono ni Narimashita.  

The writing of the adventure became the Devil's., お気の毒ですが、冒険の書は魔王のモノになりました。, Sorry but the Book of Adventures Has Become the Property of the Demon Lord, К сожалению, героем приключенческой истории стал владыка демонов, 很遗憾！冒险书的主角是魔王, Sorry, The writing of the adventure became the Devil's.

The manga revolves around Demon Lord Vellmort XIII who feels unchallenged as all Underworld territories have been conquered by previous rulers. He is bored with his daily routine, which includes indulging in luxuries and having concubines. However, he finds a new purpose when he discovers a way to conquer the Ground, inhabited by humans. Will Vellmort succeed or will he meet an untimely end due to justice?