Wisteria, Hot Water, and Demon Slayers
Hakone Kowakien Yunessun, a sprawling hot spring theme park about 90 minutes from central Tokyo, is partnering with merchandise brand AMNIBUS (run by arma bianca) for a summer-long Demon Slayer collaboration called Hakone Onsen Tan: Fuji no Hana no Kyusoku, roughly "Hakone Hot Spring Tales: Rest of the Wisteria Flowers." Wisteria is the one plant that repels demons in the series, making the tie-in a natural fit.
According to the PR TIMES announcement, the event runs nearly three months, from July 18 through October 4, 2026. It spans Yunessun's indoor and outdoor bathing areas with themed baths, collab drinks at the park's Fontana food court (each served with one of 15 random straw markers), and a special collab ticket that comes bundled with an exclusive towel featuring new artwork.
For visitors willing to extend the trip overnight, the adjacent Hakone Hotel Kowakien is offering collab hotel rooms with exclusive novelty items for guests, plus a separate plan that includes an original tenugui (a traditional Japanese hand towel).
New Yukata Illustrations and the Merch Lineup
The centerpiece of the merchandise side is a new series of illustrations depicting Demon Slayer characters in onsen yukata, the lightweight robes worn at Japanese hot spring resorts. These original drawings appear across a wide range of collectibles: trading glitter pin badges (10 types), illustration cards (12 types), mini art boards (12 types), acrylic stands in three sizes, face towels, and locker key-style acrylic keychains.
A separate "milk bottle cap motif" line references the nostalgic glass-bottled milk sold at Japanese bathhouses. That series includes acrylic keychains, a zip tote bag, a unisex t-shirt, and a waterproof multi case. There's also a themed ramune candy featuring Akaza and Koyuki, the tragic pair from the series' Upper Rank backstory.
Prices range from ¥275 (about $1.80) for a single illustration card to ¥5,478 (about $36) for the tote bag or t-shirt. Buyers who spend ¥2,000 or more per transaction receive a bonus postcard (10 designs, distributed randomly). Full-box buyers of trading items at the event venue or through the AMNIBUS online store get an additional exclusive bonus.
Looking Ahead
The event opens July 18, 2026, and full details, including visual previews of the collab baths and hotel rooms, are being posted to the Yunessun special site. For fans who can't make the trip to Hakone, arma bianca has confirmed that post-event online sales will be available through the AMNIBUS webstore, though specific dates haven't been set.
Hakone is one of Japan's most accessible hot spring destinations for international visitors, sitting on the Odakyu line from Shinjuku. The event runs during peak travel season and ranks among the more distinctive anime collaborations available this summer. No international shipping details for the merchandise have been announced.