Since time immemorial, dragons have threatened the Kingdom of Tomur, and the legendary Dragon Hunters are seen as humanity's last hope. In this world, the greatest warriors are tasked with defeating the Demon Kings to protect the realm. For their victory, a special reward awaits the Dragon Hunters at a mysterious establishment called the Soapland Kaguya, located in the remote Rosenfeld District. Here, these heroes are invited to lay down their weapons and their clothes for a different kind of service.

The story focuses on the everyday operations of the Kaguya, a traditional Japanese soapland that has somehow been transported to a fantasy world. The protagonist, a young woman named Kaguya, runs this establishment alongside her staff. The central narrative explores the culture clash as the weary dragon hunters and other fantasy denizens encounter the unfamiliar yet pleasurable services offered by the Kaguya. Rather than a grand quest to return home, the plot centers on how a rotating cast of adventurers, knights, and kings are overwhelmed by the soapland's hospitality, often finding their troubles washed away in ways they never expected. The series is known for its mature themes, being explicitly recommended for readers aged 18 and over.

Written by Shinobu Inokuma, Isekai Soapland Kaguya began serialization in 2018 in the Web Goraku Egg magazine published by Nihon Bungeisha. The original Japanese release currently spans eight volumes. The manga follows an episodic format typical of slice-of-life comedies, with each new chapter or volume introducing a different client or scenario within the walls of the soapland. These narratives often play out like a form of cross-cultural contact comedy, where the fantasy world reacts to a very specific facet of modern Japanese culture.