The protagonist Yuuri Taishi, who got summoned into another world, successfully defeated the demon lord along with three sisters Luna, Emma, and Ren. They're supposed to live their remaining lives in the current world; but due to certain reason Taishi had to go back to his own world. But one day, Taishi came home from work to unexpected guests: the three sisters from the other world. They wanted to meet Taishi so bad they performed a forbidden spell to get transferred!