Hakone Kowakien Yunessun is treating its latest Demon Slayer: Kimetsu no Yaiba collaboration as something much bigger than a quick merchandise stop. The event, titled Hakone Onsen Tan: Wisteria Flower Rest, began on July 18 and runs through October 4, 2026, turning the resort into a themed day-trip and overnight destination built around baths, sauna sessions, drinks, goods, and hotel plans. The official collaboration page lays out a visit that can stretch from the swimsuit hot spring zone to a stay at Hakone Hotel Kowakien, which changes the feeling of the event entirely. It is not just a corner booth with acrylic stands. It is a full property-wide tie-in with enough moving parts that planning ahead matters.
The center of the event is still Yunessun itself. That means the collaboration is rooted in the resort’s water-play hot spring area rather than in a separate pop-up venue. For travelers weighing whether Hakone is worth the detour, that detail matters. A visit here can be part themed attraction, part bath day, and part hotel stay if you want to turn it into a slower trip through the area. The official event page on Yunessun and the broader Demon Slayer anime site make clear that the collaboration is tied to the series’ current momentum, but the practical appeal is simple: you are paying for a place where the setting, the bath spaces, the food counter, the goods booth, and the hotel all participate in the same event.
Dates, Venue, and Ticket Details
The collaboration runs from Saturday, July 18, 2026, through Sunday, October 4, 2026, at Hakone Kowakien Yunessun in Kanagawa Prefecture. The themed bath attractions and sauna program are located inside the swimsuit-required Yunessun area, not the separate Mori no Yu bath zone, so the relevant admission is the Yunessun water area ticket. The event page lists admission for that area from 2,500 yen for adults aged junior high school and up, and from 1,400 yen for children age three and older, both tax included. Hours for the collaboration baths and sauna are 10:00 a.m. to 6:00 p.m. on weekdays and 9:00 a.m. to 7:00 p.m. on weekends and holidays.
There is also a special collaboration ticket sold with a limited face towel bonus. Yunessun says this ticket comes with a QR entry pass for smoother admission, and it sits alongside the standard One-Day Pass, Afternoon Pass, and Sunset Pass options. One key date to remember is August 8 through August 16, 2026. During that stretch, entry is fully reservation-only. The page notes that guests using the collaboration ticket do not need to obtain a separate timed admission ticket for those reservation-control dates, which can make a real difference during one of the busiest holiday windows of the season.
The hotel side of the event is also unusually specific. At the official hotel, Hakone Hotel Kowakien, the collaboration room plan runs for the same July 18 to October 4 period, with the last day limited to a one-night stay. The themed room is listed at 52,500 yen per adult and up with two meals included when two people use one room, not including hot spring tax. Yunessun originally framed this as one room per day, then announced one additional room for sale, while the plan listing itself describes the offer as limited to two rooms per day. Reservations are internet-only. The separate novelty lodging plan, which is not the themed room, starts at 29,150 yen per adult with two meals included, also based on two guests in one room and also excluding hot spring tax.
What the Event Includes
The strongest part of the collaboration is the way it uses Yunessun’s actual facilities. The first themed bath area is Fuji no Hana no Yuba (藤の花の湯場), placed in Yunessun’s indoor Midori no Terrace area. The official description presents it as a bath wrapped in wisteria flowers and surrounded by the Demon Slayer Corps. The second is Mugenjo Buro (無限城風呂), set in the outdoor Rock Cave ONSEN area and themed around the fierce clash involving Tanjiro Kamado, Giyu Tomioka, and Akaza. Both baths run through the full event period and use the same Yunessun area hours.
The sauna tie-in goes further than a poster and a character panel. Yunessun is staging a daily program called Fuji no Hana no Jokiyoku (藤の花の蒸気浴) at the outdoor Finland Bath sauna. The site says Yunessun’s heat-wave staff will hold a special training themed sauna event every day, with loyly and aufguss sessions lasting about five to ten minutes. Those sessions are scheduled twice daily at 11:30 a.m. and 2:30 p.m., and the sauna uses a floral scent. That sounds small on paper, but it is exactly the kind of timed attraction that can change how you pace a visit because you are no longer just wandering between baths.
Food and drink are part of the package too, although the site is careful to say this is not a full collaboration cafe. The featured drink is a grape-flavored item called the “Fuji no Hana” Jaki Drink, sold at Fontana inside the Yunessun swimsuit zone for 660 yen including tax. Each drink order comes with one random original tag from a set of 15. Sales hours are 10:30 a.m. to 5:30 p.m. on weekdays with last order at 5:00 p.m., and 10:00 a.m. to 5:30 p.m. on weekends and holidays with the same last-order time. Because the drink counter is inside the swimsuit area, buying it still requires Yunessun admission.
The hotel benefits are where the event starts to feel like a proper overnight package. Guests in the collaboration room receive one original novelty set per person age three and up, including a mesh bag, tenugui hand towel, fan, and one random acrylic marker charm from five designs. Guests on the non-room novelty lodging plan receive one original tenugui per person age three and up. Both hotel offers include unlimited Yunessun access during the stay, and that access begins even before the 3:00 p.m. check-in time as long as you stop at the hotel front desk first. That one detail can turn an overnight booking into a full first-day schedule instead of a late arrival.
What to Know Before Planning a Visit
The practical rules around goods are just as important as the themed features. Yunessun says some dates during the collaboration will require advance reservation tickets for the merchandise sales area in order to control crowding and protect safety. When that system is active, reservations begin at noon on the day before your visit, on a first-come, first-served basis. If a date does not require advance tickets, the reservation page will show that there is no such sale control in place. Even on reservation-control days, the goods area switches to free entry after 4:00 p.m., though Yunessun explicitly says guests should not form their own lines or wait around the area in advance.
There are tight rules attached to those goods tickets. One ticket covers one adult, and only one child age two or younger may accompany that ticket holder. The same time slot cannot be booked multiple times, and re-entry in the same slot is not allowed. Proxy entry is also banned. Yunessun says staff will verify identity with an original photo ID at reception to prevent resale and other misuse, and the name on the reservation must match the name on the identification document. It also warns that arriving late means the reservation cannot be honored, even if delays are caused by transportation or parking.
The event page also spells out limits inside the sales and drink areas. The collaboration drink is cashless only, with credit cards, e-money, and QR payment options listed on the site. For merchandise, purchase limits apply by item, and the facility warns that stock can sell out during the event period. The goods system does not guarantee that an item will still be available by the time your slot begins. Guests staying in the collaboration room get one major advantage here: during their stay, from check-in day through check-out day, they may enter the special goods booth once per day without needing a merchandise reservation ticket. For anyone deciding between a simple day trip and a hotel plan, that exemption may be one of the clearest reasons to stay overnight instead of trying to do everything in a single crowded visit.
FAQ
When does the Demon Slayer collaboration at Hakone Kowakien Yunessun run?
The event runs from July 18 through October 4, 2026.
What has been announced for the collaboration?
Yunessun has announced two themed bath areas, a daily themed sauna program, a collaboration drink with random bonus tags, merchandise sales with crowd-control rules, a limited collaboration room at Hakone Hotel Kowakien, and a separate lodging plan with Demon Slayer novelty items.
Is this better suited to a short stop or an overnight stay?
The official details support both, but the hotel options add unlimited Yunessun access during the stay, early first-day use before check-in, and in the case of the collaboration room, easier goods-booth access without a merchandise reservation ticket. That makes the overnight version meaningfully different from a quick merch run.
