Aizawa Azusa, a corporate drone who died of exhaustion from overwork in her previous life, is reincarnated in another world, where she decides to live out a slow and uneventful life forever. But then, 300 years later, she discovers that the experience she earned by defeating slimes every day just to keep up her easy lifestyle has brought her to level 99 and made her the strongest in the world. The rumors begin to spread, and soon trouble comes knocking...

Halkara's knack for inadvertently causing trouble led her to knock out the Demon King Pecora, and now she's locked in a dungeon. As Halkara's execution draws nearer with each passing moment, Azusa rushes to make a potion with her family's help and, with Beelzebub's guidance, takes it to the first-aid room where Pecora is. After tricking the demons guarding the room, Azusa finally reaches Pecora, but then...

Festival season has come to the village of Flatta. The festival has been held there for the past 250 years, but as the only person who knows its entire history since it was started, Azusa has distanced herself from it to let the villagers keep their independence. But her family has shown interest in it and seems excited to see it, so she makes up her mind to change the way she interacts with the village tradition... and thus the one-day-only coffee shop, The Witch's House, was born. Will the villagers enjoy this little shop Azusa's family has created?