Summoned as a hero to vanquish the demon king in a parallel realm, a valiant warrior successfully ends the 3-year war and defeats the malevolent ruler. However, upon his return to earth, he laments the lack of magical beings like elves, dwarfs, and demons that populated the world he saved. Frustrated by the mundane reality of earth, he resolves to venture back to the fantasy realm to fulfill his dream of assembling a harem, this time without any interruptions or deportations.