As the Tohno’s exclusive doctor, he is Shiki’s primary care physician.
It seems that he used to be a member of an organization that monitors demon hybrids, and was friends with Nanaya Kiri. However, he has since retired, and is currently some sort of shady back-alley doctor.
Since he knows the true nature of Shiki’s anemia, he has been maintaining his health with Eastern medicine. It’s not a cure, but that’s the beauty of it. Of course, Shiki’s anemia was never something that could be cured in the first place.
According to Shiki, he’s a mad doctor. Though he is foul mouthed, he is also possessed of a strong sense of duty, and it seems he is acquainted with Miyako. Probably, she used to tag along with Shiki when he visited the Jinan Clinic while he was living in the Arima household. As his appearance suggests, he has an interest in Chinese martial arts, and may even be the one responsible for teaching Miyako the basic forms.
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