Ishikawa Replaces the Ogasawara at Matsumoto

Hideyoshi’s 1590 settlement moved Ieyasu to the Kantō and the Ogasawara from Matsumoto to Koga. Ishikawa Kazumasa, a former Tokugawa officer already serving Hideyoshi, entered Matsumoto from Izumi with a holding conventionally listed at about 80,000 koku, expressing assessed rice yield.

The new lord inherited a developed center. Fukashi Castle had served the Takeda, and Ogasawara Sadayoshi recovered it after the Takeda fall, renamed it Matsumoto and began reorganizing the castle and town. Kazumasa continued this work; Yasunaga enlarged moats, built walls and gates, and carried the project forward after his father’s death.

The surviving main tower is generally assigned to Yasunaga’s building program, probably in 1593–1594, although its precise dating remains debated. Procurement and construction linked timber, masonry and residential works across several years. The transfer changed the lord responsible for an existing town and fortified base, while the Ishikawa works produced important parts of the castle still standing.