Set in a time when vampires are ubiquitous in society, treated as outcasts, and forced to keep their identities hidden—despite having signed a peace treaty two hundred years ago, following which they have satisfied their hunger with merely pig's blood.

Orange Marmalade tells the story of Baek Ma Ri, a young vampire who has faced great difficulty due to her nature. Feared and hated, the girl has been driven away from several neighborhoods and is eager to settle down with her family in their current city. The endless prejudice has left her disillusioned about friendship and love.

However, the sweet-scented blood of Jung Jae Min stirs something within her and renders her unable to resist biting into the neck of the charming man. Ma Ri must now cope with her life after this encounter, as her victim begins to fall in love with her.