Hakone Kowakien Ten-yu — the in-room onsen ryokan with the most reviews in Hakone
Have you ever wanted to try a private in-room onsen ryokan in Japan but pulled back when you saw the price? Hakone Kowakien Ten-yu is the answer many travellers have been looking for. Here, every single room comes with its own private outdoor onsen, paired with a rooftop infinity pool framed by the Hakone mountains and over 2,400 reviews on Booking that still hold at 9.1 — numbers that speak to genuine, consistent quality.
Hakone Kowakien Ten-yu sits at 1297 Ninotaira in the Kowakidani district — one of Hakone's oldest and most storied onsen zones. A free shuttle runs from Kowakidani Station in about five minutes. This isn't an intimate mountain ryokan with just a handful of rooms; it's a sizeable resort that takes the onsen experience seriously. That scale is precisely why it has accumulated over 2,400 reviews on Booking — the highest review count of any top-ranked onsen ryokan in Hakone.
"A private onsen in every room, a rooftop pool with mountain views that takes your breath away, kaiseki dinner better than expected — guests who've been come back with one message: worth every yen at this price."
The feature that shows up in nearly every Instagram post and review is the rooftop infinity pool. The edge of the pool is designed so that the water appears to blend into the sky and the Hakone mountain range behind it. First light just after dawn is the moment guests rave about most — the warm onsen water, the silence, the gold-tinged mountain air. It's the kind of scene that lodges itself in memory long after the trip ends.
Beyond the communal pool, what sets Ten-yu apart from many ryokan is that every room has its own private outdoor onsen (rotenburo). That means no queuing, no sharing — soak at two in the morning or four in the morning entirely on your own terms. The rooms themselves are in a clean, modern Japanese style with enough space to feel comfortable. This is an ideal fit for couples wanting both privacy and genuine Japanese aesthetic, without paying ¥70,000 or more.
On food — the ¥45,000 rate includes both an evening kaiseki dinner and a morning buffet breakfast. Multiple reviews single out the kaiseki as better than expected: beautifully presented, fresh seasonal ingredients, portion sizes just right. It feels like a proper sit-down experience that reminds you you're genuinely in Japan — not merely a hotel meal tacked on to fill a package.
To be straightforward: Ten-yu is best suited to travellers experiencing an in-room onsen ryokan for the first time who don't want to pay the Ginyu or Gora Hanaougi price tier. At ¥45,000 for two, with two meals, a private onsen and the rooftop pool all included, the value calculation is hard to beat compared with similarly-priced ryokan in the region.
That said, it's worth knowing what Ten-yu is not. It's a large resort — if you want the hushed, intimate feel of a small boutique ryokan where staff know every guest by name, this may not fit. During peak periods there will be other guests, and the rooftop pool can have a queue on busy holiday weekends. But for travellers who prioritise in-room onsen + reasonable pricing + a high volume of verified reviews, Ten-yu is the strongest candidate in Hakone for this combination.
One detail worth knowing: the onsen at Ten-yu draws mineral water from the Kowakidani source — a district with a long hot-spring history. The water has a mild sulphuric note, gentler than some Hakone springs, which makes it easy even for first-time onsen visitors. Many guests who came not knowing what to expect report that after the first evening soak they already didn't want to go home.
Summary from Booking & Agoda
- ✓ Private outdoor onsen in every room — the highlight guests praise most
- ✓ Rooftop infinity pool with mountain views — a truly memorable scene
- ✓ 2,400+ reviews holding at 9.1 — high consistency for a resort of this size
- ✓ ¥45,000 includes 2 meals + in-room onsen — strong value against comparable ryokan
- ! A large resort — less intimate than a small boutique ryokan
- ! Rooftop pool may have a queue on peak holiday weekends
- ! Kowakidani requires the shuttle — no shops or streets to wander nearby
- ✓ Modern Japanese-style rooms, spotlessly clean, comfortable size
- ✓ Kaiseki dinner better than expected — fresh, beautifully presented
- ✓ Ideal first in-room onsen ryokan experience without budget blowout
- ✓ Free shuttle from Kowakidani Station makes arriving and exploring easy
- ! Large resort atmosphere — if you prefer a very quiet, private ryokan this may not fit
- ! Kowakidani is away from main shopping or dining streets
- ! Book well ahead — rooms fill quickly especially on weekends and autumn weekends
- 💡If you want an intimate boutique ryokan feel — Ten-yu is a sizeable resort with plenty of guests → for hushed seclusion, consider Hakone Ginyu or Gora Hanaougi instead.
- 💡If you're visiting during a long holiday weekend or peak autumn — the rooftop pool and rooms are in high demand → book one to two months ahead; don't leave it until the last moment.
- 💡If you want to stroll local shops and streets — Kowakidani is quiet with little around it → plan separate daytime excursions to Hakone-Yumoto or Gora and use the shuttle.