Azuma Hijikata

A G.O.A. Personnel. As said in the very first episode, he sometimes is the captain of the transports and sometimes is the scary instructor who shows Candidates the right way. He's the one responsable to personally train Zero, Hiead, Clay, Yamagi and Roose. He's a smoker and also a very serious person, but also somewhat hot headed, and seems to hate when people call him "old man".

Source: Wikipedia