Kouitsu Chigyou (地行 甲乙, Chigyō Kōitsu), often referred to as Doctor Chigyou, is the head ghoul researcher at CCG Laboratory Division.
Kouitsu is a tall average man with a black shirt and pants. He wears a lab coat and has big black hair that covers his eyes completely. After the timeskip he has grown facial hair, namely a thin mustache.
He is a friendly and cooperative individual. He is also resourceful, giving Koutarou Amon the Arata when he needed it the most. Despite this apparent benevolence it has been suggested he is less interested in the ethics of science, and more interested in seeing whether a theory will actually work such as the creation of the Quinx after examining Ken Kaneki's body after his capture.
Raid of Kanou's Lab
Owl Suppression Operation
Post Rose Extermination
Chigyou was briefly mentioned during Dr. Akihiro Kanou and Tatara's conversation following the retrieval and examination of Shirazu's corpse. Dr. Kanou praised him for having invented the technique used to create the Quinx.