Working under Garak, Yatsufusa serves as an assistant to the Chief. 

He is a quiet person. He's very dedicated to his job. He talks only when needed.

His voice should sound deep with a hint of a "wimpiness" to it. This role can be left to the actor take this and create their own special twist with it as to make it more interesting, like small raspiness to it or sounding like a growl whenever they speak. Like I suggest, this is a very flexible role.