How Many Stays Survive Each Filter: The Real Numbers Behind Capacity and Facilities

There are 395 stays with a sauna. There are 213 with a pool. There are 250 with a hot spring.

There are 62 with all three.

Searching for a stay means adding conditions. Group size, sauna, hot spring, dogs allowed, close to a station. Each box you tick quietly shrinks the pool, and because the shrinking is invisible, you usually discover it as “no results” and only then start deciding what to give up.

So we counted first.

Past eight guests, more than half the field is gone

611 properties publish a capacity. Counting how many can take a party of each size gives this.

Party size	Stays available	Share
4 or more	598	97.9%
5 or more	478	78.2%
6 or more	405	66.3%
8 or more	237	38.8%
10 or more	134	21.9%
12 or more	67	11.0%
15 or more	32	5.2%
20 or more	12	2.0%

Up to four guests, almost everything qualifies. At five it is 78%, at six two thirds, and at eight it falls below 40%. Past ten you are at a fifth, at twelve a tenth, and at twenty there are twelve properties in the country.

What is interesting is that the decline is uneven. Going from four to five removes 120 properties; going from six to eight removes nearly 170 more. Japanese houses cluster around four and six sleepers, so awkward numbers like seven or nine were never really planned for.

Which means that if the group size is negotiable, dropping one person can open the world up. Going from nine to eight roughly doubles the field.

Plentiful alone, a tenth combined

Now the facilities, as recorded from official sources.

• BBQ facilities 566
• Sauna 395
• Dogs welcome 318
• Kitchen 311
• Hot spring (in-room, free-flowing or open-air, any of them) 250
• Pool 213

Every one of these clears 200, so “a stay with a sauna” is hardly rare: six in ten listings have BBQ facilities and nearly six in ten have a sauna. At this stage it still looks like a wide-open choice.

The trouble starts when conditions multiply. Sauna and hot spring: 159. Sauna and pool: 150. Sauna and pool and hot spring: 62, about a tenth of the listings.

Add “sleeps eight or more” and you are down to a few dozen. Add “dogs welcome” and “within two hours of Tokyo” and you can count the results on your fingers.

This is not a shortage of stays. It is the plain arithmetic of AND. Assume that each condition you add cuts the field by between a half and two thirds.

Which one to drop

Which brings us to practice. There is a sensible order for giving things up.

• Move the group size last. A stay you cannot all fit into is no use, though sometimes a party of seven splits into six overnight and one day guest.
• The hot spring is the easiest to drop. A day-use bath or a public bath nearby often covers it, and some properties even include a bathing pass.
• Check the pool’s season. Heating periods can be limited; the pool at VILLA SAISON FUJI, for instance, is heated from April to October. For a winter booking, dropping the pool condition costs you nothing real.
• The sauna is hardest to substitute. Its value is having it privately, whenever you want, which a facility down the road does not replicate. It belongs at the top of the keep list.

In short, keep what only exists on site and drop what has a substitute outside. Prune in that order and the field widens while satisfaction barely moves.

How to read these numbers

A note on method. The base is the 654 listings; the capacity figures cover only the 611 that publish one. Facilities are counted only where official sources state them, so absence of a mention is not absence of the facility. Saunas and hot springs get written up; kitchens and washing machines often do not.

Use these as a rough guide to how far each filter takes you. Knowing that the field shrinks means you get to choose what to give up, instead of the search doing it for you.

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