Rin's yandere mode is a state of mind that she can enter whenever she focuses hard enough. She first discovered this mode after she met Oliver, and also had Mayu's help. When she activates yandere mode, the world around her slows down a bit and loses it's color, and she is given several different powers.
Rin is able to see through walls in her yandere mode, and her mind highlights things that are important. This can include certain people or items. Sometimes when she's stuck in a situation, her X-Ray vision will highlight the next thing she should pay attention to. One of the things her X-Ray vision has become the most help with is when she has to dispose of a body. It allows her to see what what people are around, and how to evade them. When examining things, red represents targets and items to use, green represents good people, and blue represents threats.
Speed & Evasiveness
As mentioned above, when Rin's yandere mode activates, the world around her loses it's color and everything slows down a little bit. This happens because Rin's mind is set in high tension, and it's as if she has suddenly become part of the world around her. With everything slowed down, she is able to walk at her normal speeds, making it seem like she is running really fast. Sometimes, people can see a blurred version of Rin walking quickly by. However, this specific power uses up a lot of Rin "yandere energy", and sometimes gives her headaches.
Since Oliver is the boy that Rin is dedicated, she is able to track him differently than other people. When she activated her X-Ray vision, Oliver is surrounded in purple, and no other things have this effect. She is also able to track him outside of a certain area, just in case the X-Ray vision doesn't work and he's too far.