Gowasu is Zamasu's master. His purpose is to train Zamasu to become the next Supreme Kai, though he fails in the end. Gowasu is a relatively monotone character, mostly providing advice to Zamasu, asking him to make tea, and is stern with him when needed. His character is quite dry in the anime, but this series aims to make him a bit more interesting with his interest in being a GodTuber and being a little sassy with Zamasu every now and then to lighten the mood. His voice should sound old and gruff, but wise rather than senile. You can listen to Garrett Schenck for reference.