A Private Onsen Estate Within Japan's Most Celebrated National Park — Hakone Sengokuhara

① Property Highlights
This estate occupies 7,525.77 sqm (81,000 sq ft) of freehold land. Within the Quasi-National Park Special Use Zone — a designation that permits private residential use while permanently prohibiting the commercial density and vertical development that would, in time, diminish what makes this location what it is. The forest surrounding the estate is not incidental. It is structural — and it is protected.

The residence spans 759.41 sqm (8,174 sq ft) across two floors, completed in 1975 and comprehensively renovated in 2018. A double-height living and dining space anchors the ground floor, opening to a private garden. Master bedroom with walk-in closet and floor heating. A sunroom. A garage for multiple vehicles. Four Japanese-style rooms above the garage. And at the heart of the estate — a private hot spring. Natural onsen water, piped directly to the property, available within your own walls at any hour of the day or night. In Hakone, this is not an upgrade. It is the point.

Zoning permits boutique hotel and inn development within the Second-Class Tourism Use Zone — a flexibility that positions this asset for uses well beyond private residence, should the next owner’s vision extend in that direction.

7,525.77 sqm. Freehold. Private onsen. National park. Hakone Sengokuhara. ¥350,000,000.

This is not a property that comes to market. It is one that becomes available — once, quietly, to whoever is ready.

② The Neighbourhood
Hakone is not simply a destination. It is a category — Japan’s most enduring retreat for those who understand the difference between a beautiful place and a genuinely restorative one. For centuries, the volcanic landscape of the Hakone caldera has drawn emperors, artists, and the country’s most discerning residents to its thermal waters and highland forests.

Sengokuhara, the highland plateau at Hakone’s northern reaches, is the most privately held and least commercially developed of its districts — a place defined by pampas grass meadows, forest trails, and the particular quality of silence that altitude and protected land produce together.

Tokyo is approximately 110 kilometres away — 1 hour 45 minutes by car via the Tomei Expressway, or by Shinkansen to Odawara followed by the Hakone Tozan mountain bus to Sengokuhara. Close enough to reach without friction. Far enough to feel entirely elsewhere.

③ Why TonTon
This is the kind of asset that does not reach the open market through conventional channels. As the exclusive Japan licensee of Forbes Global Properties, TonTon operates at the precise intersection of deep local knowledge and a truly global network — giving our clients access not only to properties of this nature, but to the discretion, due diligence, and cross-border expertise that a transaction of this significance demands.

Our advisory team brings together backgrounds in international finance, Japanese property law, and cross-border transaction management — fluent at a native level in Japanese, English, Mandarin, Hindi, and Korean. From corporate structure establishment and tax advisory coordination to post-acquisition asset management, we provide end-to-end support across the full acquisition journey.

For clients with ambitions extend beyond the visible, our private portfolio awaits.