Kotetsu Hagane

is a Chunin from Konohagakure. He spends most of the time with his partner Izumo Kamizuki watching who enters and leaves at Konohagakure's Main Gate. Many times, most of the time during the Filler arcs, they are easily fooled with Transformation Jutsu or ignored by people who run past the gate.

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 while using Transformation Technique to look like a kid. While in this form, he triest to pick up a fight with Sasuke Uchiha but Rock Lee stops both their kicks. Later on the third test, Kotetsu and his friend Izumo Kamizuki watched over the Chunin exam, giving feedback on the Genin's qualities. During the Sasuke Retrieval arc, they are the ones who wake up both Sakura Haruno and The Fifth Hokage. The latter sends them to get Shikamaru, who is given his first mission as a Chunin: to lead the Sasuke Retrieval Squad and bring Sasuke back.

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
The abilities Kotetsu has show us so far through out the anime and manga is that he is skilled in Genjutsu, having made the 3rd floor of the Academy appear like it was the second. During the fight against Kakuzu, he uses Summoning: Conch Shell Mace in an attempt to defeat him, but Kakuzu is able to counter the attack thanks to his tentacles.

The Bandage
Since Kotetsu uses the normal Chunin uniform, his most representative trait is the bandage he wears across his face, over the nose. At one point, Asuma, Izumo and Shikamaru ask him about this, and Izumo remembers that he didn't use it when we was a kid. After a bit he agrees to take the bandage off but then Shikamaru states that knowing would be troublesome, so the reason for the bandage over the nose remains unknown.