Komoro Castle Ruins / Kaikoen Park

Komoro Kaikoen is the former site of Komoro Castle, built in 1554 during the Warring States Period, though some sources suggest the castle was originally constructed in 1487. During the Warring States Period, Takeda Shingen ordered Yamamoto Kansuke, an important vassal and master castle builder, to design the original Komoro Castle. After Toyotomi Hideyoshi united the country in 1590, Sengoku Hidehisa, a feudal lord of Komoro, undertook a major renovation of the castle and the castle town, building it into the solid fortification seen today.

Komoro Castle Ruins Kaikoen Park is listed in Japan's Best 100 Castles, the Best 100 Sites for Cherry Blossom Viewing, and the Best 100 Historical Parks. The castle is uniquely constructed as a "Sunken castle" because the entire structure is built on natural terrain below the surrounding town level, making it an architectural rarity in Japan.

While the castle keep no longer remains, visitors can still explore the labyrinthian stone walls and several original castle gates. The San-no-mon (third gate) is designated as a Nationally-Designated Important Cultural Property. Visitors can experience nostalgia while enjoying seasonal beauty including cherry blossoms in spring, autumn colors in fall, and diverse flora throughout the four seasons against moss-covered stone foundations. The park is recognized as one of Japan's top 100 cherry blossom spots, with blooms lasting until late April in Nagano's cooler climate.

The park offers a peaceful historical experience without heavy tourist crowds, featuring museums that house art and various artifacts from Komoro's history. Kaikoen functions as a beautiful municipal park surrounding the ruins of the old castle, providing an authentic glimpse into Japan's feudal past within a scenic natural setting.

The park is easily accessible with a 3-minute walk from Komoro Station. Take the Shinano Line from Karuizawa (24 minutes) or Nagano (60 minutes). The entrance fee is ¥200, with a combined ticket available for ¥500 that includes access to museums housing art and historical artifacts. Komoro city is located about 20 km west of Karuizawa in the northeast part of Nagano Prefecture.