The phrase refers to sexually explicit content related to the anime series “How Not to Summon a Demon Lord.” This type of content typically depicts characters from the series in pornographic or otherwise sexually suggestive situations. It’s a subgenre of fan-created adult material.
The existence and prevalence of this specific type of content reflects the broader phenomenon of applying adult themes to popular media. The popularity of a source material often correlates with the volume of derived adult works. Factors like character design and the perceived appeal of relationships within the original work can significantly influence the creation and consumption of such content.