Kosai

Kosai is an industrial city in Shizuoka Prefecture located on flat land between Lake Hamana to the east and the border with Aichi Prefecture to the west. The city developed around manufacturing and remains shaped by its industrial character today.

The area became a town in 1955 and merged four villages in 1972 to form the present city. This consolidation allowed the region to grow economically and develop its infrastructure more efficiently.

The Arai Barrier Museum displays objects and documents from the Edo period that show how this historical checkpoint once operated. Visitors can see how people and goods were once controlled and monitored.

The city is best explored by local bus or car since distances are spread out across the area. Visiting the Arai Barrier Museum and taking a walk along the lake shore offer a good introduction to the place.

The name Kosai literally means west of the lake, referring to its position beside Lake Hamana. This lake remains important today for commercial fishing and aquaculture operations that shape local activity.

Location: Shizuoka Prefecture

Inception: April 1, 1955

Reference: 222216

Shares border with: Hamamatsu, Toyohashi

Website: https://city.kosai.shizuoka.jp

GPS coordinates: 34.71844,137.53161

Latest update: December 14, 2025 18:47