A private natural onsen bath in every room, 34 acres of forest in Kowakudani, and the services of a full-scale luxury resort: HOTEL THE MITSUI HAKONE is shaping up to be one of Hakone’s most significant new openings. The 126-room resort is scheduled to welcome its first guests on December 15, 2026, on land with a historical connection to the Mitsui family.
This pre-opening guide brings together the confirmed details that matter when deciding whether to book—from room categories and private onsen baths to dining and the new thermal spring. It is not a stay review, and details may change before opening.
What is HOTEL THE MITSUI HAKONE?
HOTEL THE MITSUI HAKONE will be the second property under the HOTEL THE MITSUI brand, following HOTEL THE MITSUI KYOTO. The new Hakone resort will also join Marriott International’s Luxury Collection.
The setting is a major part of the concept. The site lies in Kowakudani, within Fuji-Hakone-Izu National Park, and covers approximately 135,500 square metres. According to Mitsui Fudosan, this area was once connected to a Mitsui family villa. The plan combines that history with contemporary resort design rather than recreating a traditional ryokan.
Every guest room is planned with a private natural onsen bath
The most important confirmed feature is simple: every one of the 126 guest rooms is planned to include a private bath supplied by the property’s natural hot spring source. Each room will also have a balcony or terrace.
That makes the hotel relevant to travellers who want the privacy of an in-room onsen without giving up the services and facilities of a full-scale luxury resort. It is worth reading room descriptions carefully, however. Bath style and views vary by room category, so check the room details before booking.
Rooms and suites: from 45-square-metre rooms to a 240-square-metre suite
Interiors are being designed by Yabu Pushelberg, an international studio known for luxury hospitality projects including Four Seasons and Park Hyatt hotels. The published room plan ranges from 45-square-metre Onsen Garden rooms to the 240-square-metre Presidential Suite; the largest villa is the 217-square-metre Signature Villa. The announced inventory includes:
- Deluxe: 48 m², 43 rooms
- Premier: 48–57 m², 30 rooms
- Grand: 51 m², 14 rooms
- Onsen Garden: 45–50 m², 22 rooms
- Deluxe Suite: 105 m², 7 suites
- Onsen Garden Suite: 100 m², 4 suites
- Presidential Suite: 240 m², 1 suite
- Villas: 101–112 m², 3 villas
- Terrace Villa: 101 m², 1 villa
- Signature Villa: 217 m², 1 villa
For most couples, the practical comparison will be between entry-level rooms and the Onsen Garden category. Families and small groups may find the villas more suitable, but final occupancy rules, bedding configurations and child policies should be checked for the exact date of stay.
A thermal spring spa facing Mount Sengen
Beyond the private baths, the resort plans an indoor-and-outdoor thermal spring area where swimwear will be worn. The facility is designed to face Mount Sengen, giving guests a shared, swimwear-based alternative to a conventional gender-separated onsen.
The spa plan also includes five treatment rooms, one of them designed for couples. Together with the in-room hot-spring baths, this gives the property two distinct ways to experience Hakone’s onsen culture: privately in the room and communally in a resort-style thermal area.
Dining: Japanese cuisine, all-day dining and a bar
Three dining venues have been announced:
- Sankei: a Japanese restaurant planned to serve kaiseki, sushi and teppanyaki
- RIVERINE: the resort’s all-day dining restaurant
- The Bar LAMBENT: the main bar
Menus, opening hours and reservation policies may be refined before the hotel opens. Travellers booking an early stay should check whether their room plan includes breakfast and whether dinner reservations need to be made in advance.
More than a hotel building
The large site is expected to include walking trails, a terrace deck by the Jakotsu River and a yoga terrace. Another distinctive space, Shikian, is planned as a sukiya-style retreat. These features suggest that HOTEL THE MITSUI HAKONE is being designed as a destination resort where guests spend meaningful time on the grounds, rather than simply using the hotel as a base for sightseeing.
Location: Kowakudani in the Hakone mountains
Kowakudani is in the central Hakone area, surrounded by mountain scenery and hot-spring resorts. Transport arrangements can vary by route and season, so confirm the hotel’s current access guidance and any available transfer service before travelling. In winter, build extra time into the journey when weather conditions may affect mountain roads and local transport.
If you are comparing a new international-style resort with a more traditional inn, see our guide to private-onsen ryokan in Hakone and our selection of the best luxury ryokan in Hakone.
Who should consider booking?
Based on the confirmed plans, HOTEL THE MITSUI HAKONE is likely to be most attractive to:
- Couples who want a private natural onsen bath in every room
- Travellers who prefer a contemporary luxury resort to a small traditional ryokan
- Marriott Luxury Collection guests looking for a Hakone stay
- Families or groups considering a spacious suite or villa
- Repeat Hakone visitors interested in one of the area’s most significant new openings
Guests seeking an established property with a long record of independent reviews may prefer to wait until after the opening. Early bookers, on the other hand, may value access to opening-period availability and the chance to experience the resort soon after launch.
Booking HOTEL THE MITSUI HAKONE before opening
Reservations opened on July 15, 2026, ahead of the scheduled December 15 opening. Because the hotel has not yet begun operating, compare the cancellation policy, payment terms, room category and included meals carefully. Opening dates and facilities can also change, so recheck the latest listing before finalising travel plans.
Last checked: September 2026. HOTEL THE MITSUI HAKONE is scheduled to open on December 15, 2026. This guide will be updated as more confirmed information becomes available.
