4 Hokages

The Hokage ("Fire Shadow") are the leaders of Konoha. They are generally acknowledged as the strongest in the village, although ideology and renown plays a large part in their being chosen for the position. Four shinobi and one female ninja have gained this title so far, with another shinobi gaining the title of Hokage Candidate.

During the recent war Sasuke wants to know many thing about village and his brother and all the system that is working and the facts and the figures of the shinobi world. He goes with Orochimaru
to Konoha to revive the 4 Hokages.

Orochimaru goes there and makes them alive with edo tensei.
Then sasuke asks Hashirama senju all his questions about village shinobi Uchiha Madara and Uchiha itachi, Hashirama tells him the story from where it begans.
He tells  "He founded Konoha with his childhood rival and the Best Friend Uchiha Madara.
He was born in Batsuma Senju's house and was the oldest in 4. During era of war he met Uchiha Madara and became his friend. both of them wanted peace. At that time people could not reveal their idenitity to each other because of safety purposes. Hashirama introduce himself as Rival of stone skipping , to Madara.
At that time Hashirama's younger brother was killed by Uchiha clan. He attended his Burial, then went to river. there he again met Madara. They Talked about Peace. Fight between Senjus and Uchihas continued.Until a time came Hashirama defeated the Most Powerful ninja of Uchiha Clan. After his defeat all uchiha surrenderd and Uchiha izuna was Killed By Tobirama. Then in other fight madara again got defeated by Hashirama. Then Hashirama ask him to joins him.. But Madara made an objection that if Hashirama kills himself or His brother then Madara will join allies.
hashirama accepted and tried to kill  himself but madara stopped him.
Then they made allies and Founded Konoha.

Then afterwards Madara chose another part and went that way. and the result he is here now.

Hashirama tells him about Will of Fire that passed in generations and Itachia is the best example.