I Looked Into Hakone Kowakien Yunessun

On this blog, I've been researching day-trip hot springs and 'hocance' (hotel + vacance) type facilities that I can get to without a car, for those days when I planned to go camping but just don't feel like it.

This time I looked into "Hakone Kowakien Yunessun." When I found out that a theme-park-style hot spring you can enter in a swimsuit and a proper hot spring you bathe in nude are both located on the same premises, both options caught my interest as an indoor type, so I decided to research them together.

The Short Version

It seems like this is a pretty greedy-in-a-good-way day-trip hot spring setup where you can enjoy both a pool-like area you can play in wearing a swimsuit and a proper hot spring area where you can soak nude in one facility.
As for the Rakuten Mobile signal, my measurement this time came out with a grade of C.

I've summarized the details below.

What Kind of Facility Is Hakone Kowakien Yunessun?

It's a day-trip hot spring facility located in Hakone town, apparently operated by Fujita Kanko Co., Ltd. The facility seems to be broadly divided into two areas: "Yunessun," which you enter wearing a swimsuit, and "Mori no Yu," a proper day-trip hot spring where you bathe nude without wrapping yourself in a towel.

Business hours for Yunessun are apparently 9:00 AM to 7:00 PM on weekends, holidays, and busy seasons, and 10:00 AM to 6:00 PM on weekdays, while Mori no Yu is open from 11:00 AM to 8:00 PM (last entry 7:30 PM). It seems there are irregular closures for facility maintenance. Pricing operates on a dynamic system, with the passport (Yunessun + Mori no Yu) apparently running around 3,500 to 4,000 yen for adults and 1,800 to 2,000 yen for children as a rough guide. Tickets for Yunessun alone or Mori no Yu alone are also available, apparently.

Reservations: You can basically enter without a reservation, but during busy seasons, free timed-entry tickets may apparently be introduced.
Payment: Cashless payment is the main method, and the official website apparently clearly states that cash cannot be used except at vending machines.
Phone reservations: Phone inquiries are apparently possible within the official website's reception hours, but private baths and paid rest rooms operate on a reservation system through an online booking site, and phone reservations are apparently not accepted.

Komorin

With pricing changing day to day on this dynamic system, I felt like it'd be reassuring to check the website in advance.

Highlights of "Yunessun," Where You Play in a Swimsuit

Yunessun seems to be an all-weather theme park divided into four areas: "Sea, River, Mountain, and Sky." The indoor Sea area apparently has a large space designed with a Mediterranean theme, lined with unusual baths like a coffee bath and a wine bath. The indoor River area apparently has a lazy river said to be the first of its kind in Hakone, along with a water slide for small children.

The outdoor Mountain area apparently features a water slide called "Rockies Splash" that debuted in March 2025, and since it uses heated water, it can apparently be used regardless of the season. There seems to be a height restriction of 105 cm or taller, so if you're going as a family, it might be worth checking in advance. The Sky area, located on higher ground, apparently also has an open-air observation bath with a panoramic view of the Hakone mountain range.

I Also Took a Close Look at "Mori no Yu," Where You Bathe Nude

Mori no Yu seems to be a proper day-trip hot spring set up separately from the swimsuit area. It apparently offers a garden open-air bath with views of Hakone's outer rim mountains, an indoor bath you can use regardless of the weather, a sauna, and a ceramic bath made with Shigaraki-ware pottery, among other features. My impression is that this area is designed for people who want to soak quietly.

There are apparently a total of eight private bath rooms: two within Mori no Yu and six in the annex called "Yasuragi." Pricing seems to range from about 5,000 to 11,000 yen (tax included) depending on the time slot. Barrier-free private baths are also apparently available, including a type you can use while remaining in a wheelchair. That said, the facility as a whole isn't apparently fully barrier-free, with steps and stairs in various spots, so wheelchair users might want to make an inquiry in advance.

Checking Out Rental Items and Nearby Dining and Sightseeing

Swimsuits, indoor clothing, and towels all seem to be available for rental, so it looks like you shouldn't run into trouble even if you show up empty-handed. Pricing is apparently around 1,200 yen and up for adult swimsuits, 700 yen and up for children's swimsuits, 250 yen for bath towels, and 200 yen for a set of indoor clothing. If you have a tattoo, there's apparently a rule that you can use the swimsuit area if it's covered with a rash guard, and use Mori no Yu if it's covered with a dedicated cover seal, so if this applies to you, it'd probably be reassuring to check in advance.

Nearby, the Hakone Open-Air Museum is apparently within walking distance, and affiliated restaurants and buffets are also apparently scattered around the area. The adjacent affiliated hotel apparently has stay packages that include unlimited access to both Yunessun and Mori no Yu, so it seems like you could also stay overnight and thoroughly indulge in the hot springs.

Rakuten Mobile Signal Conditions

When I checked this facility's location using the official "My Area Network Simulation" tool, the overall rating came out as "C."

The actual usability on-site could vary depending on the spot and time of day, but I wasn't able to confirm that level of detail in this research. If you use Rakuten Mobile, checking the area conditions in advance would probably help you get a clearer picture.

Komorin

A grade of C makes me a little uneasy, but maybe it's fine not to look at your phone while you're soaking in the hot spring anyway.

See Rakuten Mobile Details

Wrapping Up

To sum it up again, my impression of Hakone Kowakien Yunessun is that you can enjoy both a theme-park-style hot spring you play in with a swimsuit and a proper day-trip hot spring you bathe in nude, all in one facility. Whether it's a day you want to spend having lively fun with family or a day you want to soak quietly on your own, being able to choose the area that fits felt like part of the appeal.

As for the Rakuten Mobile signal, the result came out as a grade of C, so if that concerns you, checking with the official Rakuten Mobile tool in advance might give you some peace of mind.

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