In spring, the Mogami clan's Heijo ruins are covered with cherry blossoms.

Yamagata Castle, built by Kaneyori Shiba, the founder of the Mogami clan, is one of the largest flat castles in Japan, and parts of the ''Honmaru'', ''Ninomaru'', and ''Sannomaru'' are designated as national historic sites. Kajo Park, built on the ruins of the castle, is Yamagata City's most famous cherry blossom viewing spot, with approximately 1,500 cherry blossom trees in full bloom.

The 1,500 cherry trees include cherry blossoms with various personalities and backgrounds, such as the old Edohigan tree, which is said to have been planted by Kaneyori Shiba in the Muromachi period (1357), the Yoshino cherry tree, which was planted to commemorate the victory in the Russo-Japanese War, the yellow-green flowers of Gyoko and Ukon, and the new variety Yamagata Karen.

The most famous event is the illumination along the eastern moat that is held during the flowering season. The illuminated night cherry blossoms are reflected on the water surface of the moat, and when combined with the white walls of Higashi Otemon Gate, it creates a fantastic scenery. In addition, many elegant events are held during the day, such as the ''Kajo Cherry Blossom Viewing'', the ''Big Tea Ceremony'', and the ''Furyu Hanami Nagashi'' concert held on a boat in the moat, so be sure to check them out.