Sanada Kiyoaki served as a bushō during the Sengoku period.

Kiyoaki was born as the illegitimate son of Sanada Yukitsuna.

In 1541, after Yukitsuna was ousted from his territory and went into exile in the Agatsuma District of Kōzuke Province, he lodged with Unno 幸全.  There is a story that, during this period, Kiyoaki was born as a son of the daughter of 幸全.  If this is true, then Kiyoaki was the second son of Yukitsuna (the younger brother of Sanada Nobutsuna and the older brother of Sanada Masateru.  Later, Kiyoaki became a practitioner of shugendō (an ascetic religion incorporating elements of the Shintoism and Buddhism) on Mount Haguro in Dewa Province and founded a hermitage in this location.​

In 1591, during the Oushū Retribution by Toyotomi Hideyoshi, Kunohe Masazane and Kunohe Sanechika (siblings) who were members of the Nanbu clan opposed to their lords launched a revolt against the main branch of the Nanbu clan, an event known as the Revolt of Kunohe Masazane.  At this time, Kiyoaki supported Nanbu Toshinao of the Shinohe family.  As a reward, Toshinao granted Kiyoaki the exclusive right to lodge in the home of his lord when traveling.

In 1599, when Kiyoaki was lodging with the Nanbu family at Nanbu Castle, Kiyoaki became indignant over a trifling matter and committed seppuku near the castle gate.

The hermitage on Mount Haguro was inherited by his son, Shichirōemon, while Toshinao built a shrine to pray for the soul of Kiyoaki.  Kiyoaki has graves at the Kōtaku sub-temple at the Okunoin Temple on Mount Haguro and at the Kongō Temple in the foothills of Mount Haguro.

There is a theory that the daughter of Haneo Dōun was the formal wife of Yukitsuna as noted in an account of the Haneo family although this is not substantiated.