Hachiya Sadatsugu served as a bushō during the Sengoku period.  He was a retainer of Tokugawa Ieyasu and the lord of Mutsuna Castle in Mikawa Province.  He was commonly known as Hachiya Han-no-jō.  Sadatsugu is counted among the Sixteen Divine Generals of the Tokugawa.

In 1539, Sadatsugu was born in the village of Mutsuna in Mikawa.  He became a retainer of Matsudaira Motoyasu (later known as Tokugawa Ieyasu). 

In 1560, when Imagawa Yoshimoto invaded Owari Province, on 5/18, he obeyed Motoyasu and assaulted Marune fortress defended by Sakuma Morishige (Daigaku), a retainer of the Oda.  On 5/19, at the Battle of Okehazama, Yoshimoto was killed in the course of a consequential defeat for the Imagawa.  Sadatsugu retreated to Mikawa.  On 5/23, Mizuno Nobumoto, a retainer of the Oda, assaulted Okazaki Castle, but Sadatsugu launched an ambush at Ishize and, together with Matsudaira Nobukazu, achieved valorous results.  In the second month of 1561, he engaged in another battle against the Mizuno forces.

In 1563, Sadatsugu participated in an assault by Ieyasu against Yoshida Castle.  Next, at the Battle of Kozakai, he fought against the Imagawa clan and, together with Watanabe Moritsuna, contributed valiantly.

That same year, upon the outbreak of the Mikawa Ikkō-ikki, Sadatsugu followed the tenets of the Ikkō sect and, together with Moritsuna and others betrayed Ieyasu and joined the ikki forces and holed-up in the Shōman Temple in Harisaki.  At the Battle of Shōman Temple, he fought against and repelled Ieyasu’s forces, but out of consideration to his adoptive father, Ōkubo Tadatoshi, and other members of the Ōkubo family, he informed them of the attack and allowed them to escape.

In the eleventh month, after Kamiwada Castle was surrounded by ikki forces, Ieyasu himself deployed and routed them.  During the battle, Sadatsugu engaged in a bout against Mizuno Tadashige, but after seeing the appearance of Ieyasu, fled.  After locating the fleeing Sadatsugu, Matsudaira Kinsuke yelled: “Hachiya, are you fleeing?  Come back.”  Sadatsugu then replied: “The lord came so I fled.  I won’t show you my back” and then stabbed and killed Kinsuke.  Ieyasu approached a horse, garnered a spear, and shouted: “Hachiya, I won’t let you get away.”  Sadatsugu then hurriedly fled.

In the second month of 1564, after the death in battle of their commander, Yada Sakujūrō, the ikki forces deteriorated.  Sadatsugu, through the offices of Ōkubo Tadamasa, surrendered to Ieyasu.  Owing to urgent appeals from Tadamasa and Tadatoshi (father and son), Sadatsugu received a pardon and returned to his role as a retainer of the Tokugawa.

In the sixth month, during another assault by Ieyasu against Yoshida Castle, Sadatsugu competed with Honda Tadakatsu to serve in the vanguard.  Angered that Tadakatsu engaged in the opening clashes, Sadatsugu charged ahead, slayed two enemy soldiers, and then killed Kawai Masanori.  Prior to eliminating Masanori, he was struck by arquebus fire, sustaining serious injuries.  Subordinates assisted his retreat but he later died in the village of Mutsuna.  Sadatsugu was twenty-six years old.

Descendants

Sadatsugu had one daughter.  She returned with her mother to her hometown.  One time, when Ieyasu was engaged in a falconry expedition, he encountered the widow and daughter, and upon learning this was Sadatsugu’s child, felt pity for her.  He then sent an individual named Genichirō from the Torii clan to become an adopted son-in-law to inherit the family name.  Hachiya Yoshimasa (Han-no-jō) and Hachiya Yoshinaga were grandchildren of Sadatsugu.