"How Not to Summon a Demon Lord" is a Japanese light novel series that has been adapted into an anime. The story revolves around Sakamoto Takuma, a gamer who is summoned into a fantasy world resembling the game he plays, appearing as his powerful game avatar known as the Demon Lord. Two girls, Shera and Rem, summon him and attempt to enslave him using a spell, but due to his unique skill "Magic Reflect," the spell backfires, making them his slaves instead. The trio then embarks on various adventures, facing increasingly difficult foes and uncovering deeper plots involving demon lords and mortal races

. If your question is about the literal idea of "how not to summon a demon lord," the series humorously illustrates that attempting to control or enslave a demon lord through magic can backfire spectacularly, as the summoner might end up being the one enslaved due to the demon lord's powers like Magic Reflect

. Thus, the key takeaway from the series' premise is: do not try to enslave or summon a demon lord without understanding their powers, as it can lead to unintended consequences, including becoming their servant instead