Sry iam very busy right now, i should have answered earlier. After the Owl Suppression Operation Arc he lost his arm and got kidnaped from Eto to Dr. Kanou who made him an one-eye.
Before that plot happened, Eto kidnaped her father Yoshimura, the non-killing old owl from Anteiku (after he got defeated from the CCG), and brought him to Dr. Kanou.
Dr. Kanou wasnt thematised in the anime but his role is essential lol. He experimentalised the topic RC-cells, which is the real difference between humans and ghouls. So he took the Ukaku crawl from Yoshiumura and gave it to takizawa. After the experimentation he tortured him in specific ways in order to get takizawa loosing his humanity.
For more detail and so on, go visit this wikia link :)
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