Six hundred years ago, Kagemitsu Kumou was brought to Lake Biwa and asked to give up his life of farming to become the head of the shrine there. His new duties would include acting as a shield for the spiritual being, Botan, who resided in the shrine. An entire clan of onmyouji needed to be sacrificed to summon the normally gentle yet immensely powerful demon, but her existence was necessary to seal the cursed "Orochi," a giant snake and disaster incarnate which reawakens every 300 years.

When the Orochi was last sealed, Botan's fate became intertwined with that of Hirari Abeno, a man who professed to have loved her since his childhood. From that point forward, the two are bound to meet time and time again and eventually remember their feelings for each other. In this lifetime, will they be able to defeat the Orochi once and for all with the help of their allies? And can they break free from this endless cycle of loss and reunion to find happiness together?