Eya is a kind - hearted girl who has faced several difficulties in life. Orphaned at the age of 14, her aunt adopts her but kicks her out as soon as she turns 18. Unable to make ends meet, she gets a new job as a maid only to realize she has to look after Cross, an egoistic young man who she calls the "monster." The two do not get along at first, but as their lives become entangled, their relationship becomes more complicated.