Isawa Hisayori was a shugenja of the Phoenix Clan born in Gisei Toshi, and his duty was to protect its secrets.
In 1165 Iuchiban assaulted the city. During the Siege of Gisei Toshi Hisayori agreed with Mirumoto Kenzo to loot the temples, denying the Heartless the nemuranai kept inside. 
Hisayori was deadly injured from a chance encounter with one of Iuchiban's minions. He gave Hiruma Ashihei several scrolls to the Kuni for safekeeping until the Phoenix could reclaim them.