Lifespan: Tenshō 4 (1576) to 5/26 of Keichō 11 (1606)
Rank: bushō, daimyō
Title: Junior Fifth Rank (Lower), Chief of the Left Division of Outer Palace Guards, Chamberlain
Lord: Toyotomi Hideyoshi → Toyotomi Hideyori → Tokugawa Ieyasu → Tokugawa Hidetada
Domain: Head of Echigo-Fukushima
Father: Hori Hidemasa
Mother: Daughter of Kitajima Yoshishige
Siblings: Hideharu, Chikayoshi, Murakami Yoshitada, Kondō Masanari
Wife: [Formal] Daughter of Hasegawa Hidekazu
Children: Tadatoshi, Tsuruchiyo, Kisato
Hori Hideharu served as a bushō and daimyō from the Azuchi-Momoyama to the early Edo period. He was the first head of the Echigo-Fukushima domain, also referred to as the Takada domain. Hideharu was born as the eldest son of Hori Hidemasa.
In 1590, Hideharu joined his father, Hidemasa, for the Conquest of Odawara. Hidemasa, however, died of illness during the campaign, so Hideharu inherited the headship of the clan. On 11/6, Hideharu, similar to his father, was granted the Toyotomi surname.
In 1592, Hideharu deployed to Nagoya Castle in Hizen Province in support of the Bunroku Campaign on the Korean Peninsula. In 1593, he performed a role for the construction of Fushimi Castle.
Owing to these contributions, in the fourth month of 1598, Hideharu was promoted and transferred from Kita-no-shō in Echizen with a fief of 180,000 koku to Kasugayama in Echigo with a fief of 300,000 koku. On this occasion, he brought on as security staff Murakami Yoshiaki (90,000 koku), Mizoguchi Hidekatsu (61,000 koku), Hori Chikayoshi (30,000 koku), and Hori Naoyori (10,000 koku). Hideharu was twenty-four years old, so Toyotomi Hideyoshi assigned Hori Naomasa to serve as his deputy. Moreover, after his transfer to Echigo, Naoe Kanetsugu, the chief retainer of the former lord of the province, Uesugi Kagekatsu, collected taxes for the first half of the year, so Hideharu requested the return of this amount, but the Uesugi clan refused.
After entering his domain, Hideharu undertook construction work on a tower and moats for Kasugayama Castle. In 1600, he planned to move his base to Fukushima. During the Keichō era (1596 to 1615), land surveys under the direction of the taikō, or regent, were conducted on two levels. This differed from the former method of surveys conducted by the Uesugi. Comprehensive surveys were made of the upper and middle portions of Echigo, establishing the basis for the system of domains under the Edo bakufu. This had a significant impact on the land survey system among the domains in Echigo.
Following the death of Toyotomi Hideyoshi in the eighth month of 1598, Hideharu approached Tokugawa Ieyasu, sending Hori Naoshige as a hostage to Edo. In 1600, at the Battle of Sekigahara, Hideharu joined the Eastern Army. In the fourth month, prior to the conflict and upon secret orders from Naoe Kanetsugu, Hideharu suppressed an uprising by former retainers of the Uesugi, acting in concert with with Shintō priests and monks, in Echigo. This event is known as the Echigo Uprising or Uprising by Remnants of the Uesugi. After the conflict, Ieyasu awarded him by officially recognizing his rights to his landholdings.
The Uesugi clan was a direct factor in the uprising. In addition, Naoe Kanetsugu compelled Hideharu to pay annual taxes that caused financial hardship. In an effort to improve his finances, Hideharu had land surveys performed of the Hori domain, for which taxes were also applied to goods such as lacquerware, thereby raising tensions with residents. There is also a theory that the uprising was a reaction to pressure exerted against members of the Shingon sect as the family attempted to strengthen its control over the temples and shrines.
Hideharu died in the fifth month of 1606 at the age of thirty-one. He was succeeded by his eldest son, Hori Tadatoshi.