Shortly after the frenzied battle against the mononoke, Karakasa, the Medicine Seller returns to Ōoku. There, the aftermath of the previous incident has left its mark, causing a shift in the power dynamics inside the inner chambers. In his pursuit to defeat the mononoke, Medicine Seller delves deeper into the darkness that lurks within Ōoku, seeking to uncover the threefold truth of form, truth, and reason to confront the mononoke and resolve the crisis.