Lifespan: Tenbun 13 (1544) (?) to 8/26 of Tenshō 9 (1581)
Other Names: Yukimori
Rank: bushō, sengoku daimyō
Title: Governor of Shinano
Lord: Ashina Moriuji
Father: Nikaidō Teruyuki
Siblings: Moriyoshi, Ōkubo Sukechika
Wife: [Formal] Onamihime (daughter of Date Harumune)
Children: Ashina Moritaka, Yukichika, Yukihisa, Yukihide, Iwaki-gozen (formal wife of Iwaki Tsunetaka → second wife of Date Shigezane)
Nikaidō Moriyoshi served as a bushō and sengoku daimyō of Mutsu Province during the Sengoku and Azuchi-Momoyama periods. He was the seventh head of the Sukagawa-Nikaidō clan.
Moriyoshi was born as the son of Nikaidō Teruyuki. Based at Sukagawa Castle, he governed the Iwase District of Mutsu Province. More so than being an intrepid warrior, he was known for being a skilled official and cultured daimyō.
From 1558 to 1570, the Ashina clan governing four subdistricts of Aizu (Yama, Ōnuma, Kawanuma, and Minami-Aizu), and the Tamura clan governing the Tamura District, fought repeatedly over territory. In the second month of 1566, Matsuyama and Yokota castles were toppled by Ashina Moriuji and Ashina Morioki (father and son) and the lord of Yokota Castle captured alive. Moriyoshi then tendered as a hostage his lineal heir (later known as Ashina Moritaka) and settled with Moriuji. Thereafter, the Nikaidō came under the command of the Ashina clan.
In the sixth month of 1574, Morioki, the lineal heir of Moriuji, died early so Moritaka became the successor and inherited the Ashina clan. As a result, the Nikaidō, backed by the power of the Ashina, prevailed against the Tamura clan at the Battle of Miyoda and expanded their authority. During this battle, however, Moriyoshi sustained injuries and, in the ninth month, suddenly headed to convalesce at an onsen, or hot springs, and his senior retainers, Suda Morihide and Yatano Yoshimasa, took command in his place.
In the eighth month of 1581, Moriyoshi died at the age of thirty-eight. Thereafter, in the tenth month of 1584, following the assassination of Moritaka, the Nikaidō clan feel into decline again and, on 10/26 of Tenshō 17 (1589), was extinguished by Date Masamune.
A computer simulation game called Nobunaga’s Ambition and Dominion includes a game featuring Nikaidō Moriyoshi. This game includes a graphic of the face of each character. Moriyoshi is depicted with eyes abnormally raised and mouth wide open, as though he had gone mad. This was widely noted on a popular online bulletin board system known as 2 Channel. Kumabe Chikanaga (a kokujin, or provincial landowner, from Higo Province during the Sengoku period) was the subject of a similar facial graphic, and, together, these two characters garnered a lot of attention, raising the level of recognition of Moriyoshi. In addition, an image of Moriyoshi was produced in an ASCII text graphic.