Lifespan: Eiroku 11 (1568) to Kanei 1 (1624)
Title: Inaba-no-kami (Governor of Inaba)
Lord: Mogami Yoshiaki → Mogami Iechika → Mogami Yoshitoshi
Niizeki Hisamasa served as a bushō during the Azuchi-Momoyama and early Edo periods. He was a retainer of the Mogami clan. Hisamasa served as the lord of Fujishima Castle in the Kushibiki District of Dewa Province.
Hisamasa was born in 1568.
In 1602, Hisamasa was granted a fief of 6,500 koku in Fujishima and became the lord of Fujishima Castle, in addition to the chamberlain of Daihōji Castle (later known as Tsurugaoka Castle).
From 1607, he began construction on an irrigation dam on the Aka River. This was finally completed long after his lifetime in 1689. Nevertheless, this was named the Inaba dam based on the common name used by Hisamasa. In 1611, a retainer of the Mogami named Kitadate Toshinaga made a request to Mogami Yoshiaki to construct a canal to pull water from the Tachiyazawa River to the fields in the northern part of the Tagawa District. Owing to the difficulty of the task, many voiced opposition to the request, but based on the strong support of Hisamasa, construction began the following year.
In 1614, Ichikuri Takaharu backed Shimizu Yoshichika in a rebellion. At the residence of Hisamasa, he killed Shimo Hidehisa and Shimura Akikore (also known as Akikiyo, the son of Shimura Akiyasu) and then chased and subdued Takaharu.
In 1622, after the removal of the Mogami clan from their position as the lords of the Yamagata domain, Hisamasa was turned over to Doi Toshikatsu, lord of the Omigawa domain in Shimōsa Province. He died in Koga in 1624.