At the end of the Heian period, Kōno Michinobu supported Minamoto no Yoritomo against the Heike clan during the Genpei War and was awarded with a large territory in Iyo Province in Shikoku.

In the Kamakura period, the clan sided with Emperor Go-Toba against the Kamakura shogunate in the Jōkyū War and was suppressed, but due to the efforts of Kōno Michiari during the Mongol invasions of Japan in 1274 and 1281, the clan was restored to their position as shugo of Iyo province.

[4] During the Sengoku period, the Kōno were allied with the Murakami pirates, who dominated the Seto Inland Sea and by the Mōri clan of Aki Province; however, these alliances did not protect the clan when Chōsokabe Motochika of Tosa Province invaded from the south, the armies of Toyotomi Hideyoshi invaded from the east, and the Mōri reneged on their alliance and attacked from the north.Yuzuki Castle was surrendered to Toyotomi Hideyoshi without a fight in 1585 and the Kōno clan came to an end.

Hideyoshi chose not to use Yzuku Castle, so its ruins remained relatively well-preserved into the modern era.

[8] The castle is located a five minute walk from Matsuyama city tram Dōgo-Onsen Station.