How NOT to Summon a Demon Lord: Volume 11 by Yukiya Murasaki

The MMORPG Cross Reverie’s top player, Takuma Sakamoto, is summoned to another world and forced to play the role of the Demon Lord Diablo! After purchasing a new set of rings with Sylvie’s help (and completely unrelated to a certain coupon he got), Diablo visits the capital. But he becomes involved in a certain incident at the sorcerer’s academy and ends up attracting the attention of the Order of Palace Knights. Taken to meet the king, Diablo grandly declares:

“I am Diablo! A Demon Lord from another world!”

Accepting a quest from the king, Diablo makes his way to the south, where Rem’s hometown is. But when they see her family’s home and business, Rem declares flatly–

“They’re basically like the yakuza.”

This is the eleventh volume of the adventures of an earth-shakingly powerful Demon Lord (or at least someone who acts like one) taking on another world!