Niji

Niji shown with Lilly

Niji was intended to be Lilly's seeing eye dog in early versions of the script.  He was eventually removed from the script.  The devs have stated that he added very little to the game and made certain scenes harder to work.  In addition, his size would mean that he would mostly be covered up by the text block at the bottom of the screen. 

Etymology

Niji ( 虹 ) is the Japanese word for rainbow.