Ayakashibito Genyo ibunroku

While there were some that chose otherwise, the majority of the youkai decided it was best to become human. It was tough, but as time passed these youkai were able to blend in with the human world and live peacefully amongst them.
However, blood is thicker than water. The offspring of these youkai displayed the powerful abilities of their ancestors in times of great anxiety, often manifesting in horrible and dangerous ways, and were labeled by society as monsters.
Officially their condition was named “Acquired Systemic Special Heredity variety Syndrome”, or “ASSHS” for short and treated as a non-contagious illness, but the common people began to refer to them as Jinyous (half-youkai) nevertheless.