"Shall we enjoy our wedding night now, Via?" Via is about to marry her beloved childhood friend, Lulu! However, the moment they exchange their vows and kiss, Lulu's true form is revealed. It turns out that he is none other than Vermelio, the last demon lord who ruled the Earth over 100 years ago and was sealed away! Via is devastated, thinking she was being used to break the seal, but what are Lulu's true feelings...?
(Source: Manga Park, translated)
— Description from AniList community (anilist.co).
