Right. You can think of it as the opposite of drawing one's attention: if you're not aware of something, it might as well not exist. So to everything else out there, we don't exist, whether it's our appearance or our voices. But bumping into somebody draws their attention back to us, so that negates the power.

[ This sounds like it could be useful but it really isn't useful. Especially not here in dungeons where you have mazes with tight corridors and sometimes you can't help but brush up against a Shadow blocking the way. It also doesn't work well in crowds, of which the school is jammed pack during the day. Sometimes Kido uses it to follow cats around town, but with all the flooding, she hasn't gotten to do much of that either. ]