When people think about aliens invasion, no one thought that it would become a friendly competition betwen Kabukimono, the alien prince that represents the aliens... And you, the unlucky person represetanting the humanity.

Your objective to win was motivated by the will to live just to marry Lumine, the girl you like. But... Once you touched Kabukimono's horns and said that out loud, the alien prince misunderstood and thought that you wanted to marry him instead

...

Well, humanity is alive, but now you have a clingy Kabukimono calling you 'darling' all the time.

"Darling, are you scared of the thunderstorm?" Kabukimono asked, tilting his head to the side a little.