From November through February, once the heating goes on, guest-room air is at its driest of the year. One of the amenities guests praise in reviews during this season is the humidifier and the air purifier. HotelBank Editorial Team ran a semantic analysis of guest reviews and, for each of Japan’s 47 prefectures, counted the properties that had at least 10 reviews speaking positively about “air purifiers, humidifiers or dehumidifiers being provided” over the past 24 months (November 2024 to October 2026) and at least 20 reviews in total. Nationwide, 219 properties met both conditions. This article breaks those 219 properties down by prefecture and by hotel category, checks against review excerpts and official websites what equipment the high-mention properties provide and how, and closes with an estimate of the per-room cost of rolling it out and the room it leaves for positive reviews. It is written for hotel operators and purchasing managers reviewing their winter in-room amenities.

219 Properties, 2,981 Mentions Nationwide — Median Mention Rate 0.81%, Only 13 Hotels Above 3%

Start with the big picture. The 219 qualifying properties received 422,648 reviews in total, of which 2,981 spoke positively about air purifiers or humidifiers. The median mention rate across the 219 properties is 0.81%. By distribution, 42 properties are below 0.5%, 94 are at 0.5% to 1%, 61 at 1% to 2%, 9 at 2% to 3%, and 13 at 3% or more: most properties cluster around 1%, and only a handful exceed 3%. Air purifiers and humidifiers are by no means a majority topic in reviews, but the baseline is clear: at properties that provide them, roughly 1 review in 100 reliably praises them.

Ranked by property count, the top prefectures are Tokyo (27), Osaka (26), Kanagawa (17), Chiba (17), Fukuoka (15), Hokkaido (14), Aichi (12) and Hyogo (10) — the metropolitan areas with the largest base of properties and reviews. Converting mentions to a rate per 10,000 reviews of each prefecture (all properties, 24 months) reshuffles the order: Chiba 9.9, Tokushima 9.4, Shimane 8.2, Kanagawa 7.1 and Saitama 6.1, bringing out prefectures where specific properties attract many mentions. In Chiba, JR-East Hotel Mets Premier Makuhari Toyosuna (67 mentions) and Keisei Hotel Miramare (23) lift the prefecture figure; in Shimane, Izumo Green Hotel Morris (34) does the same.

Source: HotelBank Editorial Team research (semantic analysis of guest reviews, November 2024 to October 2026, N=219 properties, 2,981 mentions)

Source: HotelBank Editorial Team research. Mention rate (pooled) = total mentions of in-scope properties / total reviews of in-scope properties. “Per 10,000 reviews in prefecture” uses total reviews of all properties in the prefecture as the denominator. The 12 prefectures with no qualifying property are not shown

By Category — Business Hotels: 142 Properties at 0.91%; Ryokan: Only 6 but 1.54%

By category, business hotels account for 142 of the 219 properties (65%), followed by city hotels (50), resorts (16), ryokan (6), luxury hotels (4) and a hostel (1). The mention rate (total mentions in each category / total reviews) is 0.91% for business hotels, 0.51% for city hotels, 0.36% for resorts, 1.54% for ryokan and 0.42% for luxury hotels. Business hotels score higher because business travelers and multi-night guests, who spend long hours in the room, tend to write down specific amenities such as “there was a humidifier in the room” or “an air purifier was provided”. At city hotels and resorts, review topics spread across dining, views and large baths, so the mention rate for air purifiers alone is relatively lower — a difference in the mix of topics, not in whether the equipment is there. That the mix of review topics differs by category can also be seen in our analysis of loungewear mention rates by hotel category.

The ryokan figure of 1.54% rests on just 6 properties and is best read as a reference value, but at inns that put a humidifier in the room to counter dryness in Japanese-style rooms — such as Ryokan Hiyoshi (Saitama, 10 of 189 reviews) and Oboke-kyo Mannaka (Tokushima, 13 of 350) — the equipment shows up in reviews more often than at hotels. Japanese-style rooms with tatami floors and shoji screens lose humidity easily and feel especially dry once heated, so providing a humidifier appears to translate directly into words of thanks.

Source: HotelBank Editorial Team research (N=218 properties, excluding the 1 hostel)

Source: HotelBank Editorial Team research. Categories follow the MetroEngines Research property classification

Top Properties by Mention Rate — Five Mets Premier Hotels at 3–5.6%, With Humidifying Air Purifiers in Every Room

At the property level, one brand dominates the top of the mention-rate ranking. JR-East Hotel Mets Premier Tokyo Bay Shinkiba logged 68 mentions out of 1,224 reviews (5.56%), Yokohama Sakuragicho 59 of 1,331 (4.43%), Sapporo 61 of 1,395 (4.37%), Makuhari Toyosuna 67 of 1,804 (3.71%) and Gotanda 26 of 828 (3.14%): five of the 13 properties nationwide with a mention rate above 3% belong to this brand. Akihabara also ranks high with 22 of 1,091 (2.02%). In absolute mentions, too, Shinkiba (68), Makuhari Toyosuna (67), Sapporo (61) and Yokohama Sakuragicho (59) hold the top four places nationwide. Counts this high at properties with more than 1,000 reviews are no accident; they indicate the equipment is standard.

The official websites confirm it: the guest-room pages of JR-East Hotel Mets Premier Shinkiba, Sapporo and Gotanda all list an “air purifier with humidifying function” and a “hair dryer” under the amenities common to all guest rooms. In other words, it is fixed equipment in every room type, not a loan item. In reviews, guests even note the manufacturer: “there’s a Dyson humidifier in the room” (Sapporo), “I was surprised that the air purifier and hair dryer were Dyson” (Gotanda), “the Dyson air purifier placed in the room” (Yokohama Sakuragicho), “the hair dryer and air purifier are Dyson” (Makuhari Toyosuna). Because the official websites do not name the manufacturer, this article treats manufacturer references as statements from reviews. The key point is that placing a unit “with humidifying function” in every room, and choosing a well-designed model guests recognize at a glance, appears to lift the mention rate to roughly 4 to 7 times the median of the 219 properties (0.81%).

Source: HotelBank Editorial Team research (top 20 by mention rate, November 2024 to October 2026, at least 20 reviews and at least 10 mentions). Total reviews are shown because mention rates swing widely at properties with fewer than 200 reviews

The top list includes properties with fewer than 200 reviews. Annex Suehiro (Kanagawa, hostel, 13 of 177 reviews) and Abashiri Hotel Okhotsk Inn (Hokkaido, 10 of 163) both reach mention rates of 6% to 7%, but at that size a swing of 10 reviews moves the rate by several points, so they are better read as “small properties where air purifiers take up a large share of review topics” than as “high mention rate” properties. Put another way, at a small property adding a single amenity can change what guests write about.

Some properties are praised for loan or on-request equipment rather than fixed units. At Izumo Green Hotel Morris (Shimane, 34 of 1,451 reviews, 2.34%), guests write that “you can choose amenities such as a humidifier free of charge” and that “a multi-socket power strip was attached to the outlet near the humidifier and air purifier”: the practice of letting guests pick amenities at the front desk, together with a design that thinks about the power supply where the units sit, is linked to the mentions. At Hotel Cuore Nagasaki Ekimae (Nagasaki, 27 of 1,447, 1.87%), on-request lending is recorded as thanks: “thank you for preparing the air purifier I asked for” and “the free humidifier loan was a big help”. At Hotel New Green Okachimachi (Tokyo, 20 of 1,504, 1.33%), a guest gives a specific functional review: “it was a great help that the air purifier had a clothes-deodorizing mode”. At Shin-Osaka Washington Hotel Plaza (Osaka, 16 of 1,181, 1.35%), the care of putting an air purifier in a smoking room is spoken of favorably — “it was a smoking room, but it was good that there was an air purifier” — a useful example for properties that keep smoking rooms.

By absolute mentions, large properties with more than 3,000 reviews also rank high. Shinjuku Washington Hotel (Main Building) (Tokyo, 24 of 6,400) is third in Tokyo by mentions after Shinkiba and Gotanda, and Hotel Gracery Sapporo (Hokkaido, 21 of 3,090) is second in Hokkaido after the Mets Premier in Sapporo; at both, air purifiers and humidifiers are recorded with thanks at large properties used by many guests. Hotel Fukurasia Osaka Bay (Osaka, 21 of 3,353), Cross Hotel Kyoto (Kyoto, 21 of 3,529) and Mitsui Garden Hotel Prana Tokyo Bay (Chiba, 21 of 3,813) also exceed 20 mentions: even at mention rates of 0.5% to 0.7%, they generated a meaningful number of positive reviews over 24 months.

Source: HotelBank Editorial Team research (17 properties with at least 20 mentions, by mentions)

Cold/Dry Regions vs Major Metros — Metros Lead on Property Count, Cold Regions on In-Scope Mention Rate

Next, we checked whether mentions are more frequent where the air is driest. We grouped Hokkaido, the six Tohoku prefectures and the three northern Kanto prefectures (Ibaraki, Tochigi, Gunma) as “cold/dry regions”, the nine metropolitan prefectures of Tokyo, Kanagawa, Chiba, Saitama, Osaka, Kyoto, Hyogo, Aichi and Fukuoka as “major metros”, and the remaining 28 prefectures as “other”. In-scope properties number 136 in the major metros, 33 in the cold/dry regions and 50 in other prefectures, and mentions per 10,000 reviews in the region are also highest in the major metros at 4.91, versus 2.95 in the cold/dry regions and 2.02 elsewhere — so in volume, the metros lead. Two factors are at work: large chain properties that equip rooms with humidifying air purifiers as standard are concentrated in the metros, and the review base itself is larger.

Compare the mention rate among in-scope properties only (mentions / total reviews of in-scope properties), however, and the order flips: 0.87% in the cold/dry regions versus 0.64% in the major metros (the other 28 prefectures are also at 0.87%, level with the cold/dry regions). In other words, fewer properties in the cold/dry regions provide the equipment and appear in reviews, but at those that do, guests are about 1.4 times as likely as in the metros to praise it. Besides JR-East Hotel Mets Premier Sapporo (4.37%), business hotels in Tohoku prefectural capitals line up in the 1.6% to 2.0% band — Hotel Sunroute Aomori (13 of 659 reviews, 1.97%), Albert Hotel Akita (10 of 528, 1.89%), Morioka New City Hotel (11 of 592, 1.86%) and Hotel Route-Inn Yamagata Ekimae (10 of 603, 1.66%) — which suggests that guests who find a humidifier in a heated, dry room put their thanks into words more often than in the metros. For properties in cold/dry regions reviewing their winter amenities, that is a tailwind: the same investment is more likely to show up in reviews.

Source: HotelBank Editorial Team research (N=219 properties. The mention rate uses total reviews of in-scope properties as the denominator; the per-10,000 figure uses total reviews of all properties in the region)

Source: HotelBank Editorial Team research (November 2024 to October 2026)

Rollout Cost per Room — ¥30,000 to ¥85,000 per Unit, ¥17 to ¥49 per Room-Night Over 6 Years

So what does it cost to put a humidifying air purifier in every guest room? Checking retail street prices against price-comparison data as of October 2026, humidifying air purifiers from domestic manufacturers sit at around ¥30,000 for the standard class (rated for rooms of about 20 tatami) and in the ¥60,000 to ¥90,000s for the large / high-spec class, while an overseas brand’s humidifying purifier fan (model released October 2024) ran from ¥70,000 to just under ¥100,000. Corporate bulk purchases are quoted through sales agents, with prices set by volume, so here we treat retail prices as an upper-bound guide and estimate three tiers: standard at ¥30,000, upper at ¥55,000 and premium at ¥85,000.

For depreciation we use 6 years, the useful life for household electrical appliances in the National Tax Agency’s useful-life table (assets acquired for less than ¥100,000 may in some cases be expensed at once as small depreciable assets, but here we spread the cost over 6 years to smooth it). Budgeting ¥4,000 per unit per year for filter replacement, humidifier-filter cleaning and water-tank cleaning, and converting to a per-room-night basis at 80% year-round occupancy (292 room-nights per year), the cost comes to about ¥31 for the standard class, about ¥45 for the upper class and about ¥62 for the premium class. The unit alone is ¥17 to ¥49; electricity, even with 24-hour operation, runs from a few yen to a little over ten yen per day depending on model and mode, so the all-in cost per room-night stays in the tens of yen. For a 150-room property the initial investment is ¥4.5 million to ¥12.75 million; at a business hotel with an estimated settled ADR of around ¥10,000, that is a cost of 0.3% to 0.6% against one night’s revenue. For another in-room item converted to the same per-room-night basis, see our estimate of ¥13 to ¥89 per room-night for mattress replacement.

Source: HotelBank Editorial Team estimate. Unit prices are set from retail street-price ranges as of October 2026; assumes 6-year depreciation (National Tax Agency useful-life table, household electrical appliances), upkeep of ¥4,000 per unit per year and 80% year-round occupancy (292 room-nights per year). Electricity is not included

Source: HotelBank Editorial Team estimate (including upkeep, per room-night, 80% year-round occupancy)

There is precedent for rolling these out to every room at once. According to case studies published by the manufacturer, Sheraton Hotel Hiroshima installed commercial humidifying air purifiers in all 238 rooms in December 2013, Hotel Granvia Hiroshima completed installation in all guest rooms by March 2015, and Tokyu Inn Osaka put humidifying air purifiers in all 402 rooms in February 2009, each citing dryness in guest rooms as a reason. Hotel Wako in Yonago, Tottori installed one unit in each of its 100 rooms in February 2015, citing as a reason that electricity costs stayed negligible even with 24-hour operation. Among ryokan, Kagaya installed 245 units across all guest rooms in March 2014. All of these cases are more than ten years old, and current models and prices differ, but they show that fixed units in every room have been achieved regardless of category or size.

Room for Positive Reviews — From the 0.8% Median to the 3% Top Tier, 10+ Favorable Reviews a Year at 150 Rooms

Against a rollout cost of tens of yen per room-night, how large is the effect seen in reviews? In our tally, the median mention rate among properties that have the equipment and appear in reviews is 0.81%, while the top tier — fixed units of a model guests recognize at a glance — reaches 3% to 5.6%. For a 150-room property receiving 500 reviews a year, that works out to 4 favorable reviews a year at the 0.8% median and 15 a year at the 3% top tier — reviews like “the humidifier was a big help” or “an air purifier was provided, which felt thoughtful”. This is not a causal claim that the equipment directly moves rating scores; it is room in the sense that guests get more occasions to put their thanks in writing. For the relationship between in-room amenity reviews and rating scores, see our detailed analysis in Bedding Reviews: Sleep Comfort Moves Ratings 0.2 Pts, Pillows Do Not.

The review excerpts point to three factors guests value. First, the unit is “there from the start”. As at Hotel Sealuck Pal Yaizu (Shizuoka, 16 of 508 reviews, 3.15%) — “I was really grateful that a humidifier had been placed in the room from the start” — having it in the room without asking leads directly to thanks. Second, it has a “humidifying function”. Dry-season reviews focus on humidification, and the longer the stay, the more guests value it, as at Smile Hotel Nara (Nara, 19 of 1,273, 1.49%): “it was a 4-night room-only stay, but there was an air purifier with a humidifier, so it was comfortable”. Third, it is “recognizable at a glance”. The manufacturer name recurs in Mets Premier reviews because guests knew the model and saw its very presence as value. We also found that a loan-based approach can reach a mention rate in the 2% range, as Izumo Green Hotel Morris shows, when a “choose your own” practice is combined with thoughtful power strips.

For purchasing managers, the realistic option is a mix of fixed units and loans. At business hotels with high occupancy in the dry November to February season, fixed units in every room are the most likely to show up in reviews; at resorts and ryokan, where demand fluctuates through the year, it suits investment efficiency to install fixed units first in Japanese-style rooms and rooms sold on multi-night plans and cover the rest with loans. In either case, simply providing a free outlet or a power strip near where the unit sits, and adding one line on refilling the water to the in-room guide, raises the chance it appears in reviews. Now, before the heating season begins, whether to add a “humidifying air purifier” line to the in-room amenity list is a decision that can be weighed at tens of yen per room-night.

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