It is sometimes possible to become afflicted by Chi no Kokei, or "Sight of Blood".
Those struck by this ability will start to see blood stains. Deep puddles of crimson that expand across walls and floors and ceilings. Nobody else will be able to notice.
It'll just be them. The damned. The unfortunate.
Of course, after a few minutes, they'll lose this ability as quickly as they had got it.
But it's still a shocking revelation.