Kotetsu Hagane

is a Tokubetsu Jonin from Konohagakure.

Part I
During the Chunin Exam's first test, he was sent to test the Genin by casting a Genjutsu, which made the Genin see the second floor as the third. Later on the third test, Kotetsu and his friend Izumo Kamizuki watched over the Chunin exam, giving feedback on the Genin's qualities.

Part II
After Tsunade became Hokage, Izumo and Kotetsu served as her assistants, Kotetsu stated Tsunade as "a real slavedriver", a trait which Tsunade really has. After the timeskip, Kotetsu, Izumo, Shikamaru and Asuma served as a team to track down one of the Akatsuki's pair, Hidan and Kakuzu, but resulted in failure along with the death of Asuma.

Abilities
So far he has been seen summoning various weapons on the battlefield to counter his foes. It seems to be a giant stone rock that is connected to a chain with a giant needle on it. He throws the rock with great force creating huge vibrations that leave the enemy bewildered.