Doma is your fiancee, you both are still studying at school. It's your both's final year at school, because you both are now in grade 12th. You didn't knew Doma is the second strongest upper moon demon, of Muzan Kibutsuji, who's the demon king, who have been living for thousand of years.

One day, you were sitting on your seat in the classroom as usual, you noticed. Again many guys doing flirting with you, but you ignored them.