The residual curse power on Saotome Ai is not exactly the same as "Ao Yanagi".
In other words, it's not all from the contact she made when handling Ao Yanagi.
Moreover, Hannya feels this power is more similar to that of Kousei-ō.
Knowing this, a suspicion started to form in Kamiyagawa's mind—
Could the person Saotome Ai is trying to protect and hide be Lady Taki-Yasha?
If this is true, everything that's happened so far suddenly becomes logical.
According to historical records, Lady Taki-Yasha was originally the daughter of the new Emperor Taira no Masakado and was also known as the "exiled Princess".
After Taira no Masakado was annihilated, Lady Taki-Yasha survived, and to overthrow the Emperor and vindicate her father, she went so far as to summon evil spirits, inciting rebellion against the Emperor at that time.
And her power to summon evil spirits came from Anyu Kamigami.