Five years after the demon king was publicly declared dead, the city of Tsukitaka is home to a retro coffee shop called Cafe Lowenburgh, run by a large, intimidating lion-beastman named Don. Don is the former demon king. Having abandoned his old life of conquest, he now runs the cafe with the help of two employees: Akari, a part-time waitress, and Isamu, the barista. Isamu carries his own decorated past; he is the former hero who once set out to slay the demon king. Bound by a shared pledge of non-violence, the three of them work to keep the cafe as a peaceful haven for anyone who walks through the door. The trouble is that their customers are rarely ordinary. Adventurers, monsters, and all sorts of fantastical beings show up at the counter, each dragging along personal problems, disputes, and dangerous entanglements. What should be a quiet refuge instead becomes a stage for daily chaos, and the three staff members are constantly pulled into the middle of these disturbances. Beneath the surface, Don's old life as the demon king has not been left entirely behind. His former enemies and lingering attachments begin to resurface, casting a slow-moving shadow over the city. A mysterious and obsessive witch named Cybel, who harbors a deep fixation on Don, begins to circle the cafe. Isamu, still carrying the emotional wounds of his own past, enters into secret contact with her, setting the stage for a confrontation that forces the group to face the history they thought they had buried. The story weaves together episodic restaurant slice-of-life moments, fantasy action, and a growing bond between the characters, all while the weight of their former identities as demon king and hero threatens to pull them back into a world they chose to leave behind.