Happogahara is a plateau in Nikko National Park with an elevation between 1,000 and 1,200m. The plateau is famous for being able to see around 200,000 Japanese azalea flowers. In the past, there used to be a warhorse ranch there. Warhorses ate up all the grasses and trees in this area except the poisonous Japanese azaleas. As a result, Japanese azaleas flourished. 
Every year, the best time to see Japanese azaleas is in between May and middle of June. The entire area becomes bright red due to lotus flowers blooming. From the observatory, it is possible to see Nikko, Nasu mountain range, and even the Kanto Plain. There are also walking paths for people who enjoy walking or hiking in the mountains. Especially in the autumn, many people visit Happogahara for walks. Happogahara is also popular for stargazing. So in summer, people visit here to  view clear sky full of stars as they walk.