Suzumiya Kaede has little to look forward to in life aside from online gaming, and even that's slipping away from him. After a three-day-long MMO bender, he passes out and finds himself waking up in an entirely foreign fantasy world full of monsters and magic. Starting out with access to unthinkably powerful skills, he resolves to make the most of the situation and pioneer a hitherto unheard of niche: a spellsword.
In the present era, adventurers, demons, heroes, and demon lord, are no longer occupations that put one's lives at stake. With the world at peace, it is an era where conquering dungeons has been transformed into entertainment. Adventurers and monsters are able to fight with a substitute body made of magic, popularizing dungeon conquests with no deaths. Having lost his job, the "Black Mage" Remme struggled with finding another party until one day a beautiful woman appeared before him telling she had a job for him.