Lifespan: Tenshō 1 (1573) to Genna 9 (1623)
Lord: Uesugi Kagakatsu
Father: Honjō Shigenaga
Adoptive Father: Daihōji Yoshioki
Siblings: Honjō Akinaga, Yoshikatsu, Honjō Nagafusa, Yayoshi, Honjō Hisanaga, Honjō Shigenaga, Honjō Nagaakira, Honjō Nagayoshi, Honjō Toshinaga, Sagenta, sister (wife of Fukuōji Motoshige), sister (wife of Kurokawa Tamezane), sister (wife of Ishikawa Yorifusa), sister (wife of Suda Mitsutsune), sister (wife of Toi Masanori), sister (wife of Inoue Tsunamitsu), sister (wife of Nakajō Taitō), sister (wife of Kuribayashi Hisayori), sister (wife of Tsunashima Yorichika)
Wife: Daughter of Shimazu Toshitada
Children: Honjō Shigenaga (youngest brother – adopted)
Daihōji Yoshikatsu served as a bushō during the Azuchi-Momoyama and early Edo periods. Yoshikatsu was a retainer of the Uesugi clan.
In 1573, Yoshikatsu was born as the second son of Honjō Shigenaga, a senior retainer of the Uesugi clan. In a bid to exploit the fertile Shōnai Plain, Uesugi Kagekatsu joined with Daihōji Yoshiuji to oppose Mogami Yoshiaki. In 1583, however, Yoshiuji killed himself after being cornered in a rebellion by a retainer named Tōzenji Yoshinaga. Yoshiuji was succeeded by Daihōji Yoshioki (a supporter of the Uesugi) who joined with the Honjō clan and adopted Yoshikatsu. In 1585, after attacking the Shimizu clan who were relatives of the Mogami clan, were then attacked in 1587 by Yoshiaki and eliminated while Yoshikatsu narrowly escaped to the protection of his father.
The Shōnai area came under the control of the Mogami, and, toward the end of 1587, Toyotomi Hideyoshi issued a decree prohibiting conflicts between daimyō over territory or other provincial matters. Nevertheless, in 1588, Yoshikatsu joined his father in an invasion of the Shōnai, defeating the Mogami army at the Battle of Jūgorigahara and recapturing the territory. Yoshiaki sought to make a claim for breach of the decree, but was not permitted to travel to Kyōto. To the contrary, Yoshikatsu arranged through Kagekatsu to serve under Toyotomi Hideyoshi. In 1589, Yoshikatsu was bestowed with the Toyotomi name and the title of Governor of Dewa.
In 1590, the Toyotomi army led the Conquest of Odawara against the Hōjō clan following their breach of the decree in a dispute with the Sanada clan. This was followed by a campaign in the northern provinces led by the the Toyotomi known as the Oushū Retribution. During the withdrawal of forces after the Oushū Retribution, the Fujishima Uprising occurred in the Shōnai, and with the support of the Uesugi forces, the uprising was quelled the following year. The Shōnai area was forfeited, but Hideyoshi provided a fief to Yoshikatsu in Kawanakajima in Shinano Province while residing on a temporary basis in Kyōto. Through his participation in the Bunroku Campaign, he was pardoned for prior violations and thereafter joined his father in service of the Uesugi clan.
In 1600, after the Battle of Sekigahara, Yoshikatsu and his father were driven to Fukushuma Castle from where they repelled an attack by Date Masamune at the Battle of Matsukawa. In 1614, following the death of his father, Yoshikatsu rejoined the Honjō clan, adopted the name of Mitsunaga, and inherited the family. Later, his youngest brother, Honjō Shigenaga, was adopted to succeed him. This individual was the sixth son of Yoshikatsu’s father who was also known as Honjō Shigenaga but written with a different character than the name of his son.