Kim Chaewon is a demi-god that was brought to Olympus to replace her dying mother Eunbi who came from the line of Lachesis (one of the Fates sisters) and bear the task of measuring the thread of life, ultimately deciding a person's destiny, leaving her girlfriend behind, Kim Minju.

Minju and Chaewon were originally soulmates but because of the above situation, their red string must be cut.