Lifespan: Eishō 9 (1512) to Tenbun 10 (1541)
Other Names: Haruuji, Mutō Harutoki
Title: Juniro Fifth Rank (Lower), Master of the Eastern Capital Office
Clan: Daihōji (Fujiwara lineage)
Father: Daihōji 氏説 or Daihōji Sumiuji
Adopted Children: Yoshimasu (the son of Daihōji Kurō)
Daihōji Harutoki served as a bushi during the Sengoku period. He was the fifteenth head of the Daihōji clan based at Daihōji Castle (later known as Tsurugaoka Castle) in Dewa Province.
Harutoki was born as the son of either Daihōji 氏説 or his older brother, Daihōhi Sumiuji. He received one of the characters in his name from Ashikaga Yoshiharu, the twelfth shōgun of the Muromachi bakufu, and adopted the name of Harutoki.
After the departure of the Sagoshi clan who served as the governors of the Akumi District in Dewa, in 1518, a member of the Daihōji clan inherited the remnants of the Sagoshi family and adopted the name of Sagoshi Ujifusa. Ujifusa, however, sought to become independent of the Daihōji, triggering a conflict within the clan. Meanwhile, resistance arose among kokujin, or provincial landowners in Dewa, such as the Abo and Kisugi clans, against the governance of the Daihōji. Harutoki was thereby compelled to take action to suppress their actions. The Daihōji confronted the collapse of the sōryō system of regional landholdings and, in the era of Harutoki, experienced a dramatic loss of authority.
In 1532, Daihōji Castle was burned down during an assault led by Ujifusa. Owing to changes to the Aka River Basin, Daihōji Castle lost the benefit of protection provided by the natural topography, and frequently flooded, causing damage to the castle and grounds. Rather than rebuild, Harutoki moved west to the stronghold known as Oura Castle.
After conflict with the Sagoshi clan temporarily subsided, during the Daiei era (1521 to 1528), owing to his tributes to the bakufu, Harutoki was invested with the title of Master of the Eastern Capital Office. Later, he traveled to the capital and met with the shōgun, but, soon after returning to Dewa, died at an early age. In the absence of children, a retainer named Tosabayashi Zentō scrambled to arrange for a member of the clan named Daihōji Yoshimasu to become his successor.