i've saw something like this elsewhere, don't remember where:
According to the website, "other mysterious character(s) will also be added."
NAC?? SHIKI???
beware that i'm about 1% sure about this
probably it will be like Zero/Lancer, hidden until the game is out
EDIT: i confirm, in the system page of the official site, it says:
The leading actress of Nasu's original work "Kara no Kyoukai", Ryougi Shiki, crosses over to join the fight.
Her battle with Tohno Shiki, possessing the same Mystic Eyes of Death Perception, is a must-see.
Other mysterious character(s) will also be added.
SHIKI? and...
(2009.4.15 TOPICS)
Akiha school uniform version will be added.
WAT.