Puzzle #107: Blind Spot

Here's another genre taken from Naoki's website. Although I think I've seen it before somewhere else as well. It just seem familiar from a few years ago. So possibly it featured on a WPC at one point.
 The first puzzle I made I liked a lot, except I thought it was a bit too hard as the first one on my blog. So I made another one, which was much easier. But I figured I need something a little bit more challenging to post. So I made a third one, which fell a bit in between both puzzles. And instead of posting just one, I'm going to post all 3. If you solve the example and then the first 2 puzzles in order, you should gradually get all the insights to also solve the third puzzle.

Rules for Blind Spot

Easy Puzzle

 Medium Puzzle

 Hard Puzzle