Spoilers
all info are from JP twt
(I hope I didn't misstranslete it tho)
This time is about 150 years flashback in Ooku
The 3rd Emperor and Sandaime Midaidokoro really love each other very much. due to Ooku heir system suddenly enstablished, the 3rd emperor are preassured to slept with many other women to bear heir, but his official wife still love him very much the same even though it slowly makes her crazy. The turn point was when the emperor and other infected women died due to syphilis, it broke Sandaime Midaidokoro down as she was spared from syphilis but lost her beloved. Afterward she use snake motive dagger to curse Ooku and suicide.
Almost everyone in hebigami cast are morally grey, you cannot hate any or just blame them, they have their own good side.












