The version of Shiki when his mind goes blank and he starts seriously fighting for his life.
Or, one of the protagonists of Tsukihime 2.
The Mystic Eye Killers alone must have become unable to suppress his death perception, because he always has both eyes covered by bandages.
……That said, you know the game is never getting made, right?

Translator’s Notes
  1. ^ Literally Shiki the Killer.
Tsukihime Data Collection: Tsukihime Dictionary

The person Merem called Satsujinki1. Needless to say, it was that person.
One year after the story of Tsukihime, he gradually became a rumor. Such was the fame of this person.
He was still the same fool with a knife-fetish.
By the way, he still kept the whimsical Princess company while ceaselessly complained. It seemed he came all the way to Germany not because of the whim of the Princess, but due to the tip of some third party.

Translator’s Notes
  1. ^ “Killer Shiki” and “Killer Demon” are homophones, both are “Satsujinki.” Word play.
Yoi No Myoujou: Talk.

The state when Shiki’s conscious mind goes blank due to the inversion impulse. Or, a possible future version of Tohno Shiki.
If there’s ever a Tsukihime 2, he’ll be a main character. Perhaps because the mystic eye killers alone have become unable to suppress his death perception, he’ll always have both eyes covered by bandages.
Though the Nanaya Shiki that appears in Melty Blood is close to this, properly speaking “Shiki the Killer” is something that should stem from “Tohno Shiki.”

Tsukihime Dokuhon Plus Period: Tsukihime Dictionary Revised