She is the daughter of gods and demons, heartless and loveless; he is his guardian, teaching her what love is. The fetters that have been maintained for thousands of years, with the oath to never give up, intertwined reincarnations, interpreting the legend of unswerving love until death, even the gods and demons are eclipsed. When their destiny is about to come to an end, what kind of ebb and flow is waiting for them...