Desperate and in need of answers, Misao retraces their life together from the present to the distant past: their father's second marriage, their history with Sakuma Kamiki, their mother's death--and a promise they made to each other long, long ago. Old secrets and buried truths will finally come to light as Misao grows closer to understanding Ushio's struggles. And with them, a tragic tale of a fractured family unravels in reverse.