Sauna and Bathhouse Subscription "FLEXKEY" Expands Partner Facilities to 41

April 1, 2026

OPTIMIST Inc.'s "FLEXKEY," a flat-rate subscription service for saunas and bathhouses during off-peak hours, has added 14 new locations, bringing its total to 41 partner facilities. The service is also expanding its network from the Tokyo metropolitan area into the Nagoya region, aiming to turn idle facility hours into revenue while making daily sauna visits more accessible.

partnershipNQ 100/100出典：PR Times

📋 Article Processing Timeline

📰 Published: April 1, 2026 at 07:00
🔍 Collected: April 1, 2026 at 01:00
🤖 AI Analyzed: April 16, 2026 at 11:22 (370h 21m after Collected)

The off-peak hour limited subscription service "FLEXKEY" for sauna and bathhouse facilities, provided by OPTIMIST Inc. (Headquarters: Meguro-ku, Tokyo; CEO: Shunsuke Matsuyama), will begin partnerships with 14 new facilities starting in April 2026, expanding the total number of partner facilities to 41.

In addition, while this service has primarily been deployed in the Tokyo metropolitan area, partnerships with facilities in the Nagoya area will newly advance from April, progressing the formation of networks by region. Moving forward, FLEXKEY will continue to collaborate with bathhouse facilities nationwide, providing users with a new option to "make sauna a daily routine" and offering facilities a new management model that "turns idle time into revenue."

FLEXKEY is a subscription service that allows users to utilize popular partner bathhouse facilities, such as saunas, public baths, and super public baths in the Tokyo metropolitan area, every day for a flat monthly fee. Currently, early operation is exclusively available for Makuake supporters, and recruitment of new members is temporarily suspended, but it is scheduled to resume around May. Upon resumption, an upper limit on the number of members may be set to ensure smooth service provision. If you are considering using the service, please check the following official SNS accounts so as not to miss the resumption of recruitment and the latest information.

Official Instagram: https://www.instagram.com/flexkey.sauna.spa/
Official X: https://x.com/flexkey711

[Announcement of New Partner Facilities]

Starting in April 2026, the following 14 facilities have newly joined as FLEXKEY partner facilities.

[Proposals for Sauna and Bathhouse Facilities]

In many cases, sauna and bathhouse facilities face challenges such as the following:

Despite being open for regular business, there are time zones where visitor numbers struggle to grow, such as daytime on weekdays or early mornings.
Even if advertisements or SNS measures are implemented, the cost-effectiveness is hard to see, and only costs run ahead.
Even when investing in customer attraction measures, it is difficult to lead to improvements in profit margins.

FLEXKEY is designed as a system that solves these issues and can be introduced without increasing new costs or operational burdens.

With FLEXKEY, you provide* usage slots targeted only at time zones that typically have fewer visitors. A monthly contract fee is paid to the facility according to the contract details.

*It is not a private charter, but operated in a form that coexists with regular customers.

Through this system, the following benefits can be expected.

Improvement and Stabilization of Occupancy Rates: Promotes usage during low-traffic hours, enabling revenue expansion.
Creation of Sales Opportunities: Increased visitors generate secondary sales in food and beverage, merchandise, and rentals.
Zero Introduction Cost: No initial fees, monthly fees, or continuation fees are required, allowing introduction under the existing sales system.

If your facility is interested, we would appreciate it if you could contact us from the below.

Email: info.flexkey@optimist.jp

[What is FLEXKEY]

FLEXKEY is a subscription service that focuses on the challenge of "low-traffic hours such as weekday daytimes and late nights" faced by sauna and bathhouse facilities, allowing users to utilize only those time zones for a flat monthly fee. By utilizing "idle time" that is less likely to be crowded, users can enjoy high-quality sauna and bathhouse facilities at a more affordable price, and facilities can effectively utilize their idle hours, realizing a "Win-Win" for both users and facilities.

Under the concept of "Making saunas a daily routine rather than an entertainment through subscriptions," FLEXKEY aims to transform saunas from a special experience into a daily health habit. Through these initiatives, we will spread the Japanese bathing habit, contribute to the sustainable growth of the entire sauna and bathhouse industry, and simultaneously support the realization of people's wellness.