Bandō Yasunaga lived during the Azuchi-Momoyama period. He was the third son of Sogō Masayasu, a daimyō in Awa Province. Yasunaga adopted the name of Iga-no-kami. His family crest was the same as the battle standard used by Masayasu.
According to genealogies, Yasunaga departed Shōzui Castle in the ninth month of 1581 and moved to the village of Akizuki in the Awa District. His eldest son, Kamewakamaru, after growing up, adopted the name of Bandō Masahisa and became a shōya, or village head.
Based on one theory, Yasunaga may have been Miyoshi Yasunaga (written with a different character for “yasu”), and uncle of Miyoshi Nagayoshi. When Yasunaga took his own life after losing in a battle, funds from his service were given to his daughter. She used these funds to build a block of residential units in Naritō in the town of Awa and, thereafter, was referred to as Naritō-hime. The Bandō Iga-no-kami Shrine was built by their descendants in this locale.