The Tochigi patricide case (栃木実父殺し事件, Tochigi Jippugoroshi Jiken), or Aizawa patricide case, is a landmark father–daughter incest and patricide case in Tochigi Prefecture, Japan. The trial of the incident is also known as its common case name Aizawa v. Japan. In the incident, a victimized daughter, Chiyo Aizawa (相沢 チヨ, Aizawa Chiyo) (born January 31, 1939) who had been sexually abused by her father for about 15 years, eventually killed him on October 5, 1968. She was accused and convicted of murdering her father, but her sentence was suspended.