Hiraga Takayasu served as a bushō during the Sengoku period.  He was a kokujin, or provincial landowner, in Aki Province and retainer of the Ōuchi clan.  Takayasu was a member of the Numata-Kobayakawa family, later inheriting the headship of the Hiraga clan of Aki.

Takayasu was born as the second son of Funaki Tsunahira, a kokujin in Aki.  Takayasu’s birth year is unknown but based on his age when he was later sent to Yamaguchi, it was either 1531 or 1532.  His childhood name as Kamejumaru.  His cousins included Kobayakawa Masahira.

Tsunahira was the head of the main branch of the Numata family, a sengoku daimyō in Suō and Nagato provinces.  He followed his older brother, Hiraga Okihira, by aligning with the Amago clan, but when, before long, Okihira switched his allegiance to the Ōuchi, Tsunahira remained on the side of the Amago, resulting in a split with the main branch of the family.  In 1541, at the peak of the conflict between the Ōuchi and Amago families, Tsunahira was attacked by Hiraga Masahira, the head of the Numata family who succeeded Okihira whereupon Tsunahira killed himself, so Takayasu was protected by Ōuchi Yoshitaka (a sengoku daimyō and the sixteenth head of the Ōuchi clan) and, together with his siblings, was sent to Yamaguchi in Suō Province.  Despite being a hostage, he cherished by Yoshitaka.  At this time, he was nine or ten years old.  In 1549, Hiraga Takamune, a kokujin in Aki aligned with the Ōuchi died during an attack on Kannabe Castle in Bingo Province.  Takamune’s grandfather, Hiraga Hiroyasu, desired Takamune’s younger brother, Shinkurō (later known as Hiraga Hirosuke), to inherit the family, but Yoshitaka refused his appeal and placed Kamejumaru in place as the successor.  The members of the Hiraga clan were dissatisfied with this outcome but could not overtly oppose the decision.  After becoming the head of the Hiraga clan, Kamejumaru soon attended his coming-of-age ceremony and received one of the characters in his name from Yoshitaka, adopting the name of Takayasu.

In 1551, Yoshitaka was killed in a rebellion led by a retainer named Sue Takafusa, an event known as the Tainei Temple Incident.  Consistent with the wishes of Takafusa, Mōri Motonari attacked Takayasu’s base at Kashirazaki Castle, causing Takayasu to flee to Tsuchiyama Castle, a base of the Ōuchi clan in the Saijō Basin.  Takayasu attempted to make a last stand at Kashirazaki, but the castle fell to an attack by Motonari and he took his own life.  Shinkurō (Hiraga Hirosuke) succeeded Takayasu as the head of the Hiraga clan.