, also known as , was a Japanese daimyo and the first head of the Later Hà Âjà  clan, one of the major powers in Japan's Sengoku period. Although he only belonged to a side branch of the more prestigious Ise family, he fought his way up, gaining territory and changing his name in imitation of the illustrious Hà Âjà Â.
Traditionally Soun held a reputation of a rà Ânin who rose to power almost overnight in Kantà Â; however, he belonged to a prestigious family in the direct employment of the Ashikaga shogunate, and enjoyed important family connections. It has been said that Sà Âun was born at the Takakoshi castle in Okayama. His sister was married to Imagawa Yoshitada, a major daimyà  from a prestigious cadet branch of the Ashikaga family.
About 1475, under the cognomen of Ise Shinkuro, he worked for Imagawa, the constable of Suruga Province, and eventually became an "independent leader" with a number of warriors joining him.
Shinkuro became a retainer in the Imagawa clan, and when Yoshitada died in battle in 1476, Shinkurà  mediated the succession dispute between supporters of Yoshitada's son Imagawa Ujichika and Yoshitada's cousin, Oshika Norimitsu. This proved a temporary peace. When Norimitsu again attempted to gain control of the Imagawa clan, Sà Âun came to Ujichika's defense, killing Norimitsu. Sà Âun was rewarded by Ujichika with Kà Âkokuji Castle.
In 1491, he was able to take Horigoye after the death of Kantà  kubà  Ashikaga Masatomo, gaining control of Izu Province. He then adopted the given name of Sà Âun or Sozui.
He gained control of Izu Province in 1493, avenging a wrong committed by a member of the Ashikaga family which held the shogunate. With Sà Âun's successful invasion in Izu province, he is credited by most historians as being the first "Sengoku daimyà Â".
After building a stronghold at Nirayama, Hà Âjà  Sà Âun secured Odawara Castle in 1494, the castle which would become the center of the Hà Âjà  family's domains for nearly a century. In an act of treachery, he seized the castle after arranging for its lord to be murdered while out hunting.
In 1516, he laid siege to the castle of Arai, and "was virtual master of all Sagami".
In 1519, Sà Âun died in Nirayama Castle and passed on the newly built Hà Âjà  domains to his son Ujitsuna, who subsequently changed the clan name from the original Ise to Hà Âjà  and posthumously renamed his father to Hà Âjà  Sà Âun. In 1521, Ujitsuna built Sà Âun-ji temple dedicated to his father.