How Not to Summon a Demon Lord, is a Japanese light novel series written by Yukiya Murasaki and illustrated by Takahiro Tsurusaki.
The top player in the MMORPG "Cross Reverie", the person named Diablo, was summoned to another world by two summoners, Shera L. Greenwood and Rem. However, due to Diablo's prop "The Devil's Ring", the enslavement magic of the two was reflected, and Diablo became the master of the two. Although it is nominally for this, in fact, they are partners. After being summoned to another world, he crushed everything with great strength and solved the problems of Rem and Shera.