Birthday: January 18
Horoscope: Capricorn

Seishin is the local priest in Sotoba, as well as an author in writing novels. His latest work is called Shiki, which translated in English is called Corpse Demon. He has a sense of the supernatural and detects the presence of the real "shiki." He is childhood friends with Toshio Ozaki and Mikiyasu Yasumori. He is 32 years old, single, and once attempted to commit suicide in a drunken state during his university days.

He befriends Sunako during her nightly visits to his place. Although he eventually comes to discover the nature of the deaths in the village like Ozaki Toshio, unlike Toshio, Seishin refuses to take actions against the Kirishiki family. After his father turns in to the Shikis and becomes a Shiki himself, Seishin willingly visits the Kirishiki household and gets bitten by Sunako. At the end of series, he becomes a werewolf - called also jinrou - and saves Sunako from "death."