Lifespan: Kōji 1 (1555) to 10/3 of Kanei 1 (1624)
Lord: Date Terumune → Date Masamune
Father: Ayukai Morimune
Siblings: Moritsugu, Takatama Mohei, Sakon-Sōgu
Children: Tadamune, Munemasu
Ayukai Moritsugu served as a bushō during the Azuchi-Momoyama and early Edo periods. Moritsugu was a retainer of the Date clan. His family was ranked in the first seat. Moritsugu served as the lord of the Ayukai Castle in the Shimonagai shōen, or manor, of the Okitama District of Dewa Province.
In 1555, Moritsugu was the son of Ayukai Morimune at Ayukai Castle. In the ninth month of 1574, he killed an enemy in Imogawa and presented to Date Terumune. Ayukai Castle was on the border of the territory controlled by the Mogami clan, while the Ayukai clan was a retainer of the Date clan and held the first rank as a family. In 1584, when Terumune transferred his role as head of the Date to his eldest son, Date Masamune, and retired, Moritsugu hosted Terumune at Ayukai Castle until construction was completed at Tateyama Castle where he intended to retire.
On 10/14 of 1587, Moritsugu’s eldest son, Ayukai Tadamune (also known as Munenobu), was lured by Mogami Yoshiaki to revolt, where Tadamune raised arms from Ayukai. An attempt by Moritsugu to persuade Tadamune to change his plans failed, so after returning to Takatama Castle, Moritsugu pleaded with Masamune to oust Tadamune. Masamune directed forces led by Yunome Kagayasu, Izumida Shigemitsu, and Miyazawa Motozane to attack Ayukai Castle. Tadamune requested reinforcements from Mogami Yoshiaki but none came. Tadamune then gave-up attempts to defend the castle and slipped away in the darkness of night to the Mogami territory. Several hundred people remaining in the castle were killed. Afterwards, Moritsugu was praised by Masamune for his loyalty, and granted the neighborhood of Tsutsumi in the Shibata District. His second son, Ayukai Munemasu, succeeded him and preserved the first rank of the family.
On 1/5 of 1588, Moritsugu went to Yonezawa Castle to offer new year’s greetings to Masamune. In 1591, when Masamune transferred to Iwadeyama owing to the second subjugation of Ōshū by the Toyotomi, Moritsugu followed orders to move to Tsutsumi in the Shibata District. Moritsugu died at the age of seventy in 1624.
In 1600, preceding the Battle of Sekigahara, Tokugawa Ieyasu provided a signed declaration to Date Masamune to return seven locales in the former territory of the Date, including Kanda, Date, Shinobu, Nihonmatsu, Shiomatsu, Tamura, and Nagai, totaling 1,000,000 koku. According to land records, Nagai was the largest of these areas accounting for 177,933 koku, occupying almost all of the Okitama District in Dewa.