Mibu Tsunatake served as a bushō during the Sengoku and Azuchi-Momoyama periods.  He was a retainer of the Shimotsuke-Utsunomiya and the fourth head of the Mibu clan.

Tsunatake was born as the son of Mibu Tsunafusa, a sengoku daimyō and the third head of the Mibu clan.  Tsunatake received one of the characters in his name from Otsuki Imatake, a member of the Otsuki clan from which the Mibu descended.

His father, Tsunafusa, took advantage of an internal conflict between the Utsunomiya and Haga clans to occupy Utsunomiya Castle but, in 1555, suddenly died.

After Tsunatake succeeded Tsunafusa, in 1557, Utsunomiya Castle was forcibly wrested away and Tsunatake pulled back to the main base of the Mibu at Kanuma Castle.  Amidst an expansion of the influence of the Gohōjō clan, Tsunatake devised plans to become independent of the Utsunomiya but Tsunatake’s uncle, Mibu Kanetake, remained unwaveringly loyal to the Utsunomiya so came into conflict with Tsunatake.  In 1576, Tsunatake was deceived by Kanetake and Haga Takasada and assassinated at the Tenman Shrine at Kanuma Castle, after which Kanetake became the lord of the main base of the Mibu clan at Kanuma Castle.

Later that same year, Kanetake proceeded to attack Tsunatake’s son, Mibu Yoshitake, who had holed-up at Mibu Castle, but Yoshitake prevailed while Kanetake was murdered.