Did Japan's sauna market actually expand after 2020, or did an already-serious niche become louder and more photographed? This piece walks through what can be dated and counted. One disclosure first: I have advised sauna operators on growth strategy through this period, and the facility-count data below is my own tracking, published in Japanese-language market reviews since 2019.
The quiet base
Before 2020, the default Japanese sauna ran on dry heat and low humidity. Self-service löyly — pouring water over the stove's stones yourself — was close to nonexistent: a search of facility listings from the period found fewer than forty advertising it, in an industry numbering in the thousands. Cold plunges were often tepid, a formality between rounds. Aufguss, the German-rooted ritual of choreographed towel-waving, and the neppashi (heat-wave master) who performs it existed at a handful of dedicated facilities. The culture was real. What it lacked, the data suggests, was a common specification.
2019–2022: the chain reaction
The most visible trigger was a comic. Sadō — "The Way of the Sauna," Katsuki Tanaka's manga about the ritual of sauna bathing — reached television as a drama adaptation in 2019. It amplified an existing practice, and above all it gave that practice a vocabulary: totonou, the state of deep clarity after a full sauna–cold–rest cycle, went from an insider's term to a word colleagues could say to each other and be understood. Variety shows, lifestyle media, and corporate promotions picked the vocabulary up at speed.
The tracking numbers show what followed. Facilities listing self-service löyly went from roughly 37 in early 2019 to 731 by January 2022, and 1,347 by that November. These are listings on Sauna Ikitai, Japan's largest facility-review platform — not construction counts, and the platform's own coverage grew over the same period. The shift accelerated through the pandemic years, when private and outdoor sauna formats stayed open while much of Japan's other leisure closed.
Three structural shifts inside the room
Self-service löyly went from rare to expected. The listing count above traces the reversal.
The cold plunge became an engineering investment. Chillers, better insulation, and genuinely cold water replaced the tepid tub at the facilities leading the boom. A chiller is now one of the more expensive line items in a sauna build-out.
Aufguss moved to the center of the room. Heat became performance. At flagship venues, Aufguss sessions are now scheduled, timed, and marketed like a live show, with the neppashi as the headline act.
A market with a definition
My reading is that these three changes converged into something the pre-2020 market lacked: a common competitive specification. Newer destination facilities compete, in large part, on the same three axes — a room that reliably holds heat, a plunge that is genuinely cold, and a löyly or Aufguss program that gives the middle of the session a shape.
These numbers are a practitioner's field tracking, not an audited market report. Whether the user base actually expanded, or a serious niche simply became more visible, is a question the listings don't settle — that verification is the work of the author's ongoing Japanese-language market analysis, published on note.
For a visitor, none of this needs to stay theoretical. Go in quiet, watch how regulars move before you move, and give the full cycle — heat, cold, rest — a real chance before deciding what you think.
— Takayama Sauna, Editor-in-Chief
Lead photography by Anne Nygård on Unsplash.