Tetsu is a member of AL4, along with Sugimori Ren and Asaka Narumi. His moniker is the General.
Tetsu, Ren, and Kai are childhood friends from middle school. When Kai transfers in, Tetsu and Ren approach Kai to cardfight. Tetsu is the first to cardfight with Kai, but loses to Kai.
Later, when Ren gains Psyqualia, Tetsu is thrown back literally after Ren beats him in a cardfight. Kai, not able to stop Ren's drastic change in character, leaves the team and moves back home. Kai suggests that Tetsu leave with him, but Tetsu refuses to abandon Ren.
Tetsu is shown to be fearful of Ren's Psyqualia, but nevertheless, remains at Ren's side.