Shiobara Onsen is located in the southwest of Nasu Shiobara area, Nikko National Park.
Around Onuma Park which has wetlands and swamps at 960m above the sea, there is a forest of Japanese horse chestnut, beech, and quercus crispula. It is chosen as "Best 100 of Japanese Walking in the Woods" and has rich nature.
Also, Onuma is a amphibians' breeding place and around June, "Polypedatid" climb trees to spawn like bubbles on branches. When I saw it for the first time, I was like "Oh my gosh! Are these eggs? On branches?" I couldn't believe it.
"Polypedatid" spaws on a branch above a swamp. At hatching time, tadpoles fall into the swamp. They leave to their offspring. Eggs are about 150-200.
If it is a good timing, you can observe eggs on a branch form a boardwalk.
When you see the frogs, be quiet and observe gently please.