There Was a Cute Girl in the Hero's Party, So I Tried Confessing to Her

The story centers on Yōki, a man reincarnated into a fantasy world. Yōki did not reincarnate as a hero or the demon lord, however, but as the demon lord's underling. When a hero's party attacks the demon lord's castle, Yōki is naturally there to fight against the heroes. However, when he sees the priest Ceclia who is part of the hero's party, he falls in love at first sight.