The Battle of Odakura occurred on 3/26 of Eiroku 3 (1560) in Odakura in the Shirakawa District of Mutsu Province.  The conflict was waged by the Nasu clan against the allied forces of the Ashina and Shirakawa-Yūki clans.

Prelude

Theories regarding the causes of the Battle of Odakura include as follows:

• The Ashina clan, in a bid to gain control of the Nasu area, joined the Shirakawa-Yūki clan to invade.
• The Shirakawa-Yūki clan sought to subdue the Nasu clan (with whom they were in conflict) and invaded with reinforcements from the Ashina clan.
• The Nasu clan invaded based on a plan to expand the territory under their control.
• The Nasu clan acted in coordination with Satake Yoshiaki who plotted an advance into Mutsu Province.

All of the foregoing are theories and it is uncertain which clan was the aggressor.

Course of events

Owing to an inferior number of troops, the Nasu forces suffered a rout during which their commanding general, Nasu Suketane, sustained injuries.  At one point, he even considered taking his own life.  Capable retainers led by Ōzeki Takamasu rushed to his aid so it ended without further incident.

According to a historical account of the Nasu clan, the Nasu forces mounted an offensive to eject the Shirakawa-Yūki forces and proceed as far as Kawagohara.  This account, however, as an account of the Nasu clan, was compiled in the Edo period and its authenticity is uncertain.

Aftermath

After the battle, Suketane censured Ōzeki Takamasu and Ōtawara Tsunakiyo (siblings who were his retainers), assigning responsibility for the losses to them and triggering a confrontation with the Ōzeki and Ōtawara clans.  Takamasu responded by taking members of the Upper Nasu family and abandoning Suketane and colluding with the Satake of Hitachi Province.  On 5/15, Suketane encouraged Matsumoto Michikatsu, a retainer of Takamasu, to plot his assassination.  When Takamasu learned via Satake Yoshiaki of the plot, he had Okino Yoshishige guard him.  To expel Suketane, Takamasu made plans to back Satake Yoshihisa (later known as Nasu Suketsuna), the younger brother of Satake Yoshishige. 

Suketane engaged in repeated battles against Takamasu (who obtained reinforcements from Yoshishige).  This included attacks below Karasuyama Castle, but Suketane repelled them.  On 8/24 of Eiroku 9 (1566), Takamasu joined Satake Yoshikata and the Shimotsuke-Utsunomiya clan to attack Suketane, but Suketane routed them at Kaminaga in Shimotsuke Province.  In 1567, Takamasu and Satake Yoshishige fought against the Nasu clan at 大崖山 but were repelled.  Having lost in all of their battles against Suketane, in 1568, Takamasu and Tsunakiyo settled on the condition that Suketane retire while Takamasu underwent the rites of tonsure and apologized for his crimes of resistance.  Thereafter, Takamasu served as a leading figure among the Seven Clans of the Nasu in support of the Nasu clan.  In the era of Nasu Sukeharu, he wielded the most authority in the Nasu clan.  In 1576, Takamasu moved his base from Shirahata Castle to Kurobane Castle.  In 1578, he transferred the headship of the clan to his second son, Ōzeki Kiyomasu but, nevertheless, continued to maintain his grip on power.