Obu Dōetsu served as a bushō during the late-Muromachi and Sengoku periods.  He was a retainer of the Kai-Takeda clan.

During the Sengoku period, the Takeda clan, serving as the military governors of Kai Province, were engaged in a broad conflict with powerful kunishū, or provincial landowners, in Kai.

On 10/17 of Eishō 12 (1515), Takeda Nobutora attacked Ōi Nobutatsu and Ōi Nobunari (father and son), kokujin in Nishigōri, and surrounded the main base of the Ōi clan at Toda Castle.  After the Takeda cavalry rode into Fukada, Dōetsu and Obu Genshirō (Dōetsu’s lineal heir), along with Imai Nobufusa, Ozo Bishū, Oyamada Yamato-no-kami, and members of the Amari clan, were all killed in the ensuing battle.

Dōetsu was the natural father or near relative of Obu Toramasa and Yamagata Masakage (siblings) who served Takeda Nobutora and his son, Takeda Harunobu (later known as Takeda Shingen).  During this rebellion, an individual named Obu Genshirō was killed in action, which name matches a pseudonym used by Masakage.  Therefore, it is noted that Genshirō may have been the father of Toramasa and Masakage.  In this case, Masakage’s year of birth would have to be later than is understood so questions remain.

The family temple of the Obu clan known as the Tentaku Temple is located in Kamezawa in the city of Kai in Yamanashi Prefecture.  A Buddhist mortuary tablet for Obu Toramasa is kept there.  In this tablet appears a name with the character “etsu” which is deemed to refer to Dōetsu.