He is the original Tohno Shiki, the one who has Tohno blood and becomes possessed by Roa in Tsukihime. To be distinguished from the other Tohno Shiki, who is actually Nanaya Shiki.
Usually written as 遠野 シキ (Tohno SHIKI, upper case), in order to distinguish him from Tohno Shiki, the protagonist of Tsukihime, whose name has the same pronunctiation.
