The heroine of this doujin is an arachne, a half-spider, half-man monster girl. Even better, she’s an arachne call girl, meaning our protagonist ordered her services. The thing is, when she offered him a “special course”, he accepted it on the spot, not considering the consequences. Only when he finds himself in a room filled with spider silk, wrapped up in thread and unable to move, with a naked arachne looking at him with the eyes of a hungry predator, does he realize that maybe he’s in over his head. (Source: Fakku)