Sagan is a shinobi from Iwagakure.
Sagan seems to be a calm shinobi and he was shocked while watching the five Kage fight Madara. After seeing how powerful Madara is, he stated that it was all over for him and his comrades.
Sagan has long, brown hair which reaches into his back with a bang on the left side of his face. Attire-wise, he wears the standard attire of the Iwa-nin complete with a two-sleeved shirt, with mesh armour underneath it. He also wears his red forehead protector in a bandanna style.
Sagan is a sensor-type shinobi of some skill, evident on the battlefield when he detected Madara Uchiha and Mū's location and alerted the other shinobi present. 
Though not a medic, he was also able to deduce the Tsuchikage's state from looking at him as well.
Fourth Shinobi World War: Climax
During the Fourth Shinobi World War, Sagan was assigned to the Fourth Division. He was one of the few shinobi of that division to survive Madara Uchiha's assault on the battlefield. Making his way over to where Ōnoki was, he informed the other that the Tsuchikage was still alive, though gravely injured. He later alerted those present when Madara and Mū had reconstructed, and watched on in despair as Madara continued his assault on the depleted division. When the five Kage assembled on the battlefield, Sagan looked on in amazement as the battle between the titans unfolded, noting that he felt severely out of place. Later, Sagan was seen pursuing Mū alongside Dodai and the Hokage Guard Platoon, and witnessed Mū's soul ascending when the Impure World Reincarnation was released.