One day, Keitarou unexpectedly transferred to a different world where he met Nia, a half-demon girl, who urged him to "make a child" with her. The two of them went traveling in search of gateways to different worlds when Rosette, another half-demon girl, appeared... The girls of a different world fight over the valuable "human male" using their sex appeal. (Source: Takeshobo, translated)