Having spent a blissful morning at Tsunashima Gensen Yukemuri no Sho in Yokohama, I found myself swaying along on the Tokyu Oimachi Line. Among the scenery rolling past the window were the streets around where I used to live. The familiar supermarket, the roads I walked so often — memories from that time came flooding back with startling clarity. I could even recall the mood I carried back then, the expression on my face as I went about my days. Comparing my past self to who I am now, I felt a faint wave of melancholy at how much time had flowed by. But I couldn't afford to linger in sentimentality. The vector of my heart was already pointing firmly toward the next destination. That destination was Sauna Metsä Oimachi TRACKS — an urban wellness spa that opened in March 2026, located inside OIMACHI TRACKS, a complex directly connected to JR Oimachi Station. The operator is Oakland Kanko Kaihatsu, the company behind Spa Metsä and Ryusenji no Yu. I'd seen it featured on TV and had been eagerly looking forward to visiting after spotting the stunning photos on their official website. I stepped off at Oimachi Station and made my way up to the 4th floor of the gleaming new commercial complex. Passing through the entrance at the far end, I was met with an atmosphere that felt like a high-class members-only fitness club — refined, exclusive, and slightly intimidating. The sheer sophistication of it nearly made me hesitate before walking in. After checking in, I strolled through the fragrant interior toward the large bathing area. The locker room, too, was immaculately appointed, like the spa facility of a luxury hotel. This was unmistakably a stylish urban hideaway for discerning adults. Stepping into the bathing area, I was greeted by a dimly lit space where blue neon signs glowed — the world of Spa Metsä, fully realized. That said, I'll be honest: the actual space felt smaller than I had imagined from the photos I'd seen beforehand. The rest chairs placed throughout the room were a welcome touch, but they also contributed to a slight sense of coziness that bordered on cramped. Even so, the facilities were impeccable. There are two types of sauna: Japan's first tram sauna, and a kelo sauna built with rare timber. The cold plunge options come in three temperatures — 8°C, 15°C, and 22°C. And apparently, all of them use ultra-soft water, so I was already looking forward to that smooth, silky feeling against my skin. Since I had already bathed thoroughly in Yokohama that morning, I headed straight for the sauna room after a quick rinse. First up: Japan's first tram sauna. Opening the door, a wave of intense heat hit me immediately. The room temperature was around 90°C with space for about 15 people. What was truly remarkable was the interior — hanging straps like those on a train were suspended from the ceiling, completely recreating the atmosphere of a train car. And through the window at the front, you could see the Oimachi Station railyard, so you could actually gaze out at real train lines from inside the tram sauna. What an immaculately realized concept. As I sat there soaking up the heat, I noticed buttons mounted throughout the sauna room. It seemed that pressing one would trigger an automatic löyly. With few others around, I didn't hesitate. And that's when I had a first-of-its-kind experience. A voice announcement — reminiscent of a train PA system — began to play: "Please don't forget to totonou," "Next stop: cold plunge, cold plunge." I burst out laughing right there in the sauna. There is simply no other sauna this packed with entertainment value. After steaming myself to my limit, I headed to the cold plunge. With so many temperature options it was hard to choose, but I've always been a 15°C person at heart. As I submerged myself in the cold water, the heat built up in the tram sauna gradually dissipated. The soft water lived up to its reputation — the texture against my skin was incredibly smooth, like being enveloped in water. From there I moved to the dedicated rest area and slipped into my first totonou of the session. I did not forget to totonou, for the record. For my second set, I tried the kelo sauna. It's a compact space for about 9 people, with a mild temperature of around 80°C, and self-löyly is available. With kelo, you naturally expect that distinctive, rich fragrance above all else. However, perhaps because this is a brand-new sauna freshly built, I couldn't really detect the characteristic kelo scent. The same thing happened when I visited Mainichi Sauna Tokyo Makuhari — it may simply be that you can't fully enjoy the kelo aroma when the sauna is fresh. Perhaps the scent deepens over time as the room is seasoned by the sweat and heat of many visitors. Either way, missing out on the kelo fragrance this time was a slight disappointment. For my third set, I returned to the tram sauna. As soon as I entered, someone must have pressed the button — the löyly sequence kicked off again. The same announcements rang out once more. This gimmick is genuinely brilliant. The other guests also seemed to be enjoying it in their own way as the waves of heat washed over them. I'd become completely hooked on those announcements myself, and right before leaving the sauna, I pressed the button one last time to soak in the heat and sound of the löyly once more before stepping out. And so, it was time for the final set. This sauna trip was nearing its end. I'd close it out in the kelo sauna, doing a self-löyly and spending some quiet time with myself. When I opened the kelo sauna door, I found it completely empty — a perfect scenario to cap off the final set. I settled deep into the bench and, without thinking, exclaimed out loud, "Ah, this is the best!" No one was around, so why not. Putting my feelings into words made the sense of happiness swell even further. Riding the wave, I called out next, "Ah, this feels incredible!" And right at that moment, the door clicked open and an older gentleman walked in. I braced for an awkward atmosphere — but barely a second after entering, the man himself bellowed out, "Ah, it's so hot, so hot!" I was mentally screaming at him that saying it out loud only makes it feel hotter, when he then proceeded — astoundingly — to start a self-löyly. Here was a man saying he was hot and then turning the temperature up even higher: the complete contradiction between his words and his actions was almost too much to bear in silence. But by then I had also hit my own heat limit. "Man, it's hot," I muttered to myself like a soliloquy, and stepped out of the sauna. The final set ended on a slightly flustered note, but my spirits couldn't have been higher as I finished.

I made my way from Oimachi to Shinagawa, then boarded the Shinkansen back to Shin-Osaka. For me, having been in the sauna until just moments before, the travel time on the return Shinkansen was the ultimate indoor rest — naichiyoku at its finest. I sank deep into the Shinkansen seat, letting a body perfectly primed by the sauna simply rest. I gazed absently at the scenery flowing past the window and spent a while in a blissful, vacant state of totonou. I have an irresistible fondness for this quiet stretch of time that arrives at the end of a journey. At 18:00, I arrived at Shin-Osaka Station. Having rested well on the Shinkansen, I was now ravenously hungry. Time for sauna meshi. The fun I'd had at Yokohama Chinatown the night before was still fresh in my mind, and I found myself craving Chinese food all over again. As it happens, Shin-Osaka Station is home to Fan Fan, a renowned restaurant famous for exceptional Chinese cuisine. I had visited it about eight years ago, and I have yet to encounter a mapo tofu that surpasses the one I had there. The moment that memory resurfaced, my feet were already carrying me toward the restaurant. The mapo tofu at Fan Fan, tasted for the first time in years, was every bit as extraordinary as I remembered. The stimulation of the spices and the deep, rich umami hit my sauna-sharpened palate with tremendous force. Utterly delicious Chinese food — the final piece of this trip had clicked perfectly into place. And with that, this sauna journey came to a close. It began in Yokohama, passed through Oimachi, and drew its curtain in Shin-Osaka. I touched memories of the past, encountered a new sauna, and brought everything to a close with an exceptional meal. As a single page in the story of life, it was a day as fulfilling as any I could ask for. What kind of place will I discover next? My quest to explore the world of saunas is far from over.