Gatz is a Servitor Unit. His duty is to assist and protect Mistress Yuna, and he obeys her commands despite his own feelings on certain matters. He has the ability to transform into a silvery, flying reaverbot.

For the most part Gatz appears only in his "reaverbird" form. He serves Yuna well and seems to have excellent combat capabilities, although he loses to Geetz when the two go head to head.