Ōtsu Castle

Ōtsu Castle is a water castle in Otsu that once stood on the shores of Lake Biwa, fortified with stone walls. The site contained multiple defensive structures and a four-story observation tower that monitored the surrounding area.

The castle was founded in 1586 by Asano Nagamasa and replaced the older Sakamoto Castle in the region. It played a key role in controlling the southern areas of Lake Biwa during a time of major political change in Japan.

The site holds meaning as a place where water defense strategies once shaped regional power. Visitors can observe how natural geography was transformed into military advantage through careful construction.

The site is located where the current JR West Otsu Station stands and is easily reached on foot. Visitors should allow time to explore the ruins and read the informational panels that explain the construction methods used.

When Lake Biwa's water level drops during certain seasons, the original stone walls of the main castle emerge from the water, revealing how medieval builders worked. This occasional unveiling lets visitors see construction techniques that are normally hidden beneath the surface.

Location: Otsu

Inception: 1586

Founders: Asano Nagamasa

GPS coordinates: 35.01206,135.86425

Latest update: December 7, 2025 10:02