Koutarou Amon (亜門 鋼太朗, Amon Kōtarō) is a former First-Class Ghoul Investigator. He was Kureo Mado's last partner and his last partner was Akira Mado. He was subsequently declared dead by the CCG, though his body was never recovered, and was posthumously promoted to Special Class for his distinguished service. During the Rushima Landing Operation, he reappeared alive as an artificial one-eyed ghoul.