Japanese, meaning "truth."
Sub-Area of Chess Board
It is believed that killing him triggers the Murder Hall event, but it may be possible to trigger it without his death.
His name means "truth," which is the opposite of Usotsuki's, whose name means "Liar.'
He shares his fileset with Nanashi in the game's CharSet, which may or may not suggest that the two are related somehow, though this has not yet been confirmed.