Karpoi was a young matoran that was the chronicler of his village. when he stumbled upon an odd ask the mask attached itself to his face and transformed him into a mysterian. A mysterian is a tall toa-like creature that attaches itself to a host and changes the hosts original color and adds in the color black and then demorphs the attitude of the host and makes them have evil thoughts. But since, Karpoi had such a caring sole and heart light he couldn't be crazified and so he joined the ranks of toa and became an elite.