Yamagata Castle, also known as Kajo, was founded in 1357 by Shiba Kanetori and expanded by Mogami Yoshiaki into one of eastern Japan's largest flatland castles. Now Kajo Park, it is famed for cherry blossoms.

Built in 1357 by Shiba Kanetori. Mogami Yoshiaki greatly expanded it during the Sengoku period. Yoshiaki sided with the Eastern Army at Sekigahara, becoming a 570,000-koku lord, but the clan was abolished after his death. It became an army garrison in the Meiji era and is now Kajo Park.