Katahara Onsen is a scenic hot spring village in the coastal area of Mikawa Bay, considered one of the largest in the Gamagori Onsen area. The area around the Hodagaike Pond, part of Katahara Onsen, is highly regarded as the "Home Place of the Hydrangeas" (Ajisai-no-Sato), due to the 50,000 bushes of exuberant flowers that proudly ornate the boardwalk around the water body when in their full bloom. During that time, the Hydrangea Festival (Ajisai Matsuri) is held in order to celebrate them, starting on June 1st and going for a whole month until June 30th. The event is quite famous, attracting an excess of 100,000 tourists yearly and operating temporary bus lines during the period in order to facilitate access. The hydrangeas are also artificially illuminated after dusk, giving the place a whole different atmosphere. And if you're lucky, you may even get to see the beautiful twinkling firefly swarms that chose this incredible place as habitat.