Kosai City, located in the western part of Shizuoka Prefecture, merged with other municipalities in 1955 and was relaunched in 2010. Bordering Lake Hamana and surrounded by mountainous terrain, the entire region is rural. Thanks to a well-balanced mix of industries, the region maintains a stable economy. Its main specialties are clams and eels. Tourist attractions in the area include Honkoji Temple and Honkaji Temple. With many historical buildings, the area attracts tourists from all over Japan. The Suwa Shrine Dedication Fireworks, a traditional event that has been held since the Kyoho era, is known for its majestic scenery.