Yuusha Party ni Kawaii Ko ga Ita node, Kokuhaku shitemita.

Youki dies in his original world and awakens in a fantasy realm as a powerful demon serving as a guard in the Demon King's castle. With no interest in conquest or glory, he is content with a quiet existence until the Hero's party attacks the castle and he casually defeats them.

Before sending the party home, Youki notices their priestess Cecilia and falls for her instantly. From that moment, his greatest problem is no longer the war between humans and demons, but how to confess to a girl who is supposed to be his enemy. Through secret meetings and misunderstandings, he tries to build a relationship without betraying himself or placing Cecilia in danger.