oshi castle was completed by narita akiyasu around 1479. the narita family ruled over the area of gyōda as retainers to the odawara hōjō clan. the castle made use of marshes and swamplands in its surroundings and was considered impregnable. in 1590, toyotomi hideyoshi dispatched his senior retainer ishida mitsunari with an army of 23,000 troops to seize the castle. in the siege of oshi, the castle’s 619 samurai and 2000 local conscripts held off numerous attacks, and the castle surrendered only after word that their overlords had been defeated at the siege of odawara.