A Cossackbot who learned how he could create his own soul and emotions and become one with the spirit world. He is Kage's (Shadow Man's) teacher.
When Dr. Cossack died he lived alone in a hut along with Farao (Pharaoh Man), Todo (Toad Man), Akaru (Bright Man), Zugaikotsu (Skull Man), Daibingu (Dive Man), Hokori (Dust Man), Doriru (Drill Man), Ringu (Ring Man), and Kalinka. When Kalinka died, eight of the Robot Masters traveled to different countries, but Zetnen stayed where he was. One night, Zetnen saw Kalinka in a dream. She taught him how to be one with the spirit world and reality. As time passed he reawakened a Robot Master that was also created to be a Japanese ninja as he was. That Robot Master's name was...Kage (Shadow Man).
Whatever the one holding the controller does.
He doesn't really act or look pretty old, but from back in 200X (the current time is 22XX, during when the Star Force series occured), he's pretty old. I created him to be a master of the art of the shadows and becoming one with the spirit.