The Hakone Museum under the open sky was opened in 1969 and became Japan's first Museum, in the literal sense of not having a roof over the heads of visitors. Framing for exhibits of sculptures and installations – is nature itself, namely forest, located high in the mountains. Depending on the time of year, the visitor in this exhibition hall will surround each time different landscapes.

As stated on the Museum's website, he tries to recreate a harmonious balance of nature and art. On its territory, which is more than 70 thousand sq. meters, there are more than 120 sculptures by masters from around the world – such as Rodin, Pablo Picasso, Henry Moore and others, and also several Japanese artists. In addition to the exhibition hall under the open sky, the Museum also has five pavilions, including the pavilion, dedicated to the works of Pablo Picasso. For children there is a Playground, and on it placed the installation by Japanese authors is of an unusual shape, bright, functional, made using materials that are not classical sculpture – colored mesh, for example. For tired tourists near the Museum shops, cafés and restaurants, and even a SPA service in the form of hot baths work-weary travel legs. However, delivers tourists to the mountain comfortable train.

It seems that the motto of the Museum was the phrase said by Henry Moore that sculpture is the art under the open sky. The collection includes 26 works by this British sculptor.

A collection of Pablo Picasso, consisting of more than 300 works, the Museum has acquired from his daughter Maya Picasso. It includes paintings, sculptures, ceramics, prints, coins, and many portraits of the Maestro that have been created in the last seventeen years of his life and which are also important for understanding his life and work.