Miyakami no Yuみやかみの湯

Miyakami no Yu opened in January 2019 with a deliberate pitch: health and beauty, not just a hot dip. The outdoor bath draws from the same mixed Yugawara spring that supplies the valley - ナトリウム・カルシウム-塩化物・硫酸塩温泉, pH 8.2, source temperature 61.7°C - but the honest water-treatment certificate posted on-site tells the full story: 加水・加温・循環 for the outdoor bath and the same plus 塩素消毒 for the indoor bath. The facility markets the outdoor bath as 源泉かけ流し; in practice it is a warm (42°C), lightly diluted, non-chlorinated circulating bath. That distinction matters if you are chasing the mineral-saturation experience of Mamanenoyu upstream - it does not matter much if you want a pleasant, well-maintained open-air soak with a mountain view.

The variety is the actual draw, and it is the richest in Yugawara's day-use roster. The indoor section holds 'みやかみラムネ湯,' Yugawara's first carbonated spring - a 38°C tub where CO₂-enriched water promotes circulation and leaves a mild tingle. Alongside it, a cold water bath at 20°C enables 交互浴, the alternating hot-cold cycle that regulars return for. Private rental baths (two rooms, priced separately) offer a fully enclosed option for groups, couples, or guests with privacy preferences. Deeper into the menu: a mud pack steam sauna (ラッスール) using mineral-rich muds and a Thai herb tent therapy, both bookable at additional cost.

From the outside, Miyakami no Yu reads more spa than sentō. The riverside site along the Chitose River gives the outdoor bath mountain sightlines - '山の景色を眺めつつ川風に吹かれてまったり' (mountain scenery while a river breeze drifts over you) - and the interior leans toward the clean-lines aesthetic of a contemporary wellness space. A second-floor lounge makes it easy to string two hours of bathing to two hours of rest, which some visitors do deliberately. One early reviewer noted road noise from the adjacent road, and the 2019 newness means none of the layered history that gives Mamanenoyu or Kogome no Yu their atmosphere.

Admission is ¥1,100 tax-included plus a separate Yugawara 入湯税 of ¥150. The facility opens at 7:00 and runs until 21:00 (last entry 20:30) with no fixed closed day - year-round in principle, with irregular maintenance closures. Children under elementary school age are not permitted in the main baths; they can use a private rental bath with an adult. Tattoos are explicitly not permitted per the official site. Free parking for 22 vehicles across two adjacent lots.

The mud pack sauna and herb tent require advance booking and are priced well above the base entry - build those into a morning session if the schedule allows. The private baths book in one-hour slots starting from 7:00, so early arrivals can claim a riverside window before the weekend crowds arrive. The Instagram account @yugawara_miyakaminoyu posts closures when they occur; worth a check before a day trip built around the facility.

Miyakami no Yu occupies the modern end of a spectrum that runs from the institutional (Kogome no Yu's municipal bath) through the toji extreme (Mamanenoyu's ¥300 single-bath, call-ahead etiquette bath) to the contemporary spa here. It is the right pick for first-time visitors who want variety and predictability over mineral intensity, for groups with mixed bathing preferences, or for a half-day that layers an onsen session with rest and a meal nearby. For maximum source-water quality, the commute upstream to Mamanenoyu is about fifteen minutes on foot.

住所: 神奈川県足柄下郡湯河原町宮上42-15

電話番号: 0465-20-7538

営業時間: 7:00-21:00 (last entry 20:30)

タオル: Towel rental available. Shampoo, conditioner, and body soap provided. Razor and other small items available at front desk.

浴槽の種類: 露天風呂, 内湯, 炭酸泉, 水風呂, 貸切風呂, 泥パックスチームサウナ, ハーブテント

源泉: 湯河原温泉 混合泉（土肥サービランス）

泉質: ナトリウム・カルシウム-塩化物・硫酸塩温泉 (弱アルカリ性低張性高温泉)

源泉温度: 61.7°C

pH: 8.2

温泉の取り扱い: mixed

「山の景色を眺めつつ川風に吹かれてまったり」

Watching the mountain scenery while a river breeze drifts over you.

「スタイリッシュで隠れ家的な雰囲気」

Stylish with a hideaway ambiance.

「源泉かけ流しの露天風呂と、屋内に炭酸泉と水風呂。あ〜さっぱりした。体が軽くなりました」

Source-flow outdoor bath, then indoor carbonated spring and cold bath. Ah, I feel clean - my body felt lighter.

「お風呂で２時間、休憩処で２時間…溜まっていた疲れが流れ出た気分です」

Two hours bathing, two hours resting - it felt like the accumulated fatigue had finally drained away.

「薄く温泉感がなく、ただのお湯のようでした」

Diluted, lacking any hot spring character - just ordinary hot water.

「濾過循環・加水加温・消毒ありのフルコース」

The indoor bath: full-course - filtration, circulation, dilution, heating, disinfection.

「機能的・清潔・使い勝手上々」

Functional, clean, excellent ease of use.

複数のプラットフォームで収集した情報に矛盾があった箇所です。

• Water handling vs. 'source flow' marketing: The facility's headline claim is '源泉かけ流し日帰り温泉.' The spring analysis certificate posted on-site (read by jake.cc 2023) shows: outdoor bath (露天風呂) - 加水・加温・循環 (no chlorine); indoor bath (内湯) - 加水・加温・循環・塩素消毒. Neither bath is kakenagashi in the strict sense (source flow with no dilution or recirculation). The outdoor bath is the better option - non-chlorinated, source-water-present, warm at ~42°C. The indoor bath should not be characterized as source-quality water. We describe the outdoor bath as the primary bath and note both water-handling tiers factually without moralizing (rubric §9).
• Source temperature - Nifty structured record vs. spring analysis certificate: Niftyonsen's structured record lists source temperature as 40°C. The spring analysis certificate posted on-site says 61.7°C, and Nifty's own classification entry lists the spring as '高温泉,' which by definition requires ≥42°C. The 40°C figure is almost certainly a data entry error in Niftyonsen. We publish 61.7°C (pH 8.2) from the on-site certificate as authoritative.
• Admission - base price plus Yugawara 入湯税: Base admission is ¥1,100 (tax incl.) per adult - confirmed by Yugawara official tourism site, Niftyonsen, and supersento. The Yugawara onsen tax (入湯税) of ¥150 per adult is charged separately on top. Surugabank's column lists ¥1,500+tax, which is stale - likely predates a price adjustment. Publish ¥1,100 + ¥150 separately to avoid ambiguity. Children under elementary school age are not permitted in main baths; private rental bath (additional cost) is the available option for families with very young children.
• Carbonated spring (みやかみラムネ湯) - authenticity and experience: Marketed as '湯河原初の炭酸泉' (Yugawara's first carbonated spring). Jake.cc (2023) questions the characterization, noting negligible CO₂ levels and absence of visible bubbles. The Niftyonsen 2023 reviewer noted bubble formation. The likely truth: CO₂ content produces a mild tingle and light effervescence but not the strong carbonation of a high-CO₂ purpose-built facility. Experience is pleasant and the health claims (circulation, blood pressure) are directionally valid, but first-time visitors expecting a strongly fizzy bath may be underwhelmed.
• Tattoo policy: Explicitly not permitted. Official site states: '入れ墨・タトゥー・タトゥーシール・ボディペイントをされている方、暴力団関係者の方のご入館をお断りしております。' This is one of the clearest tattoo prohibitions across the reviewed Yugawara onsen - no conditional exceptions, no 'call ahead,' no private-bath workaround mentioned.
• Extras pricing - mud sauna, herb tent, private baths: The mud pack steam sauna (ラッスール) and Thai herb tent are both priced well above the base ¥1,100 admission. Surugabank's column (which may be stale on this as on admission pricing) lists ¥8,000-14,000 for the sauna and ¥3,000-4,000 for the herb tent. Private rental baths: ¥2,200-2,750 room charge + ¥1,100 per person. Visitors who only use the main baths (outdoor + carbonated + cold) will pay ¥1,100+¥150 and leave; visitors who add extras should budget 3-5x that. Confirm current pricing at the facility.

• みやかみの湯 公式サイト
• Niftyonsen - みやかみの湯
• Surugabank 井伊部長の温泉グルメ探訪
• jake.cc 温泉備忘録 - みやかみの湯 (2023)
• supersento.com - みやかみの湯
• 湯河原温泉 公式観光サイト - みやかみの湯