How NOT to Summon a Demon Lord

How NOT to Summon a Demon Lord (also referred to by its more literal English translation, The King of Darkness Another World Story: Slave Magic) is an isekai light novel series, written by Yukiya Murasaki and illustrated by Takahiro Tsurusaki. The plot concerns Takuma, a shut-in who has built a hugely powerful demon lord in the fictional MMORPG Cross Reverie and spends his time griefing random players, until he finds himself trapped in the world of the game by two young girls who attempt to summon his character. After the spell rebounds on them and they become Lord Diablo's slaves instead, Takuma takes pity on them and journeys with them through the fantasy world to find a solution, while covering up his real-life social awkwardness with hammy bluster.

The series has since been adapted into both manga and anime form.