After a morning sauna session at Baden Garden in Tokorozawa, I grabbed a coffee at a nearby café and made my way to Higashi-Kurume Station. My next destination: Spadium Japon, one of the largest spa facilities in Japan. I hopped in a taxi at Higashi-Kurume Station, and before long the building came into view. It was a three-story stadium-style structure — as massive as a baseball park. The name "Spadium" says it all: the concept is a stadium-scale space where crowds of people can unwind and enjoy the hot springs. Seeing it in person, I was genuinely taken aback by the sheer size. The thought of what lay inside had me buzzing with excitement. But the moment I arrived, I had to rub my eyes. The entrance to Spadium Japon is on the third floor, and there was a line snaking all the way down to the first. Even popular restaurants rarely draw queues like this. I hate waiting in lines, and for a split second I considered turning around — but then I remembered I had absolutely nowhere to be. I have plenty of time. What's an hour in line? I joined the back of the queue and waited. An hour later, I finally made it inside. The interior was staggering. The open, airy space was lined with all kinds of restaurants and eateries, packed with guests eating, lounging in chairs, and just letting time drift by however they pleased. Everyone looked genuinely happy and relaxed. People were willing to stand in that line for a slice of tranquility. In that sense, the potential of Japanese onsen and sauna culture really does feel limitless. When people are tired, they seek out hot springs and saunas. Now, time to get in the water. Spadium Japon markets itself under the tagline "premium natural spring water," and the three things worth paying attention to are the natural hot spring, the cold plunge bath, and the sauna. The water in particular comes from the same source as the spring water of Higashi-Kurume — the only water in Tokyo to be selected for the Heisei 100 Famous Waters of Japan list. I was curious just how refreshing that cold plunge would feel. I started by rinsing off and easing into the natural hot spring. It must have had carbonation in it — tiny bubbles clung to my skin all over, and within just a few minutes my whole body was radiantly warm. Once I was warmed up, I headed to the sauna. It fit around 30 people and was arranged in five tiers. Sitting at the top, I could feel a powerful, enveloping heat. The humidity was remarkably high, and the room was filled with the scent of pine aroma. It smelled so good I never wanted it to end. The size of the room, the heat, the fragrance, the humidity — every element was spot on, ticking every box for what makes a great sauna. The automatic löyly every 10 minutes was a wonderful touch too: it kept the humidity consistently high and delivered a fresh hit of pine aroma each time. Absolutely excellent. After the sauna, I moved to the cold plunge. What kind of refreshment would this award-winning water deliver? There were two options: 12°C and 16°C. I started with the 16°C bath. Sure enough, I could feel that distinctive, high-quality-water refreshment — the kind you only get with truly clean water. I've experienced exceptional cold plunge baths all over Japan, and Spadium Japon has earned its place among them. A top-tier cold plunge is a completely different experience from one filled with ordinary tap water. It's like submerging yourself in mint water — a cool, tingling sensation on the skin that lingers long after you step out. Humans are animals after all; our bodies respond naturally to quality water. Next came the outdoor cool-down. The open-air bath area at Spadium Japon had a wonderful atmosphere, and the weather that day was gorgeous. Sitting in a reclining chair soaking up the sun, I drifted in and out of consciousness more than once. Afterward I kept cycling through the sauna and cold plunge in a kind of meditative trance, and by the time I came to my senses, I'd completed five sets. The quality of every single element — the hot spring, the sauna, the cold plunge, the outdoor bath — was exceptional. I finally understood why people are willing to stand in that line.

After a morning sauna session at Baden Garden in Tokorozawa, I grabbed a coffee at a nearby café and made my way to Higashi-Kurume Station. My next destination: Spadium Japon, one of the largest spa facilities in Japan. I hopped in a taxi at Higashi-Kurume Station, and before long the building came into view. It was a three-story stadium-style structure — as massive as a baseball park. The name "Spadium" says it all: the concept is a stadium-scale space where crowds of people can unwind and enjoy the hot springs. Seeing it in person, I was genuinely taken aback by the sheer size. The thought of what lay inside had me buzzing with excitement. But the moment I arrived, I had to rub my eyes. The entrance to Spadium Japon is on the third floor, and there was a line snaking all the way down to the first. Even popular restaurants rarely draw queues like this. I hate waiting in lines, and for a split second I considered turning around — but then I remembered I had absolutely nowhere to be. I have plenty of time. What's an hour in line? I joined the back of the queue and waited. An hour later, I finally made it inside. The interior was staggering. The open, airy space was lined with all kinds of restaurants and eateries, packed with guests eating, lounging in chairs, and just letting time drift by however they pleased. Everyone looked genuinely happy and relaxed. People were willing to stand in that line for a slice of tranquility. In that sense, the potential of Japanese onsen and sauna culture really does feel limitless. When people are tired, they seek out hot springs and saunas. Now, time to get in the water. Spadium Japon markets itself under the tagline "premium natural spring water," and the three things worth paying attention to are the natural hot spring, the cold plunge bath, and the sauna. The water in particular comes from the same source as the spring water of Higashi-Kurume — the only water in Tokyo to be selected for the Heisei 100 Famous Waters of Japan list. I was curious just how refreshing that cold plunge would feel. I started by rinsing off and easing into the natural hot spring. It must have had carbonation in it — tiny bubbles clung to my skin all over, and within just a few minutes my whole body was radiantly warm. Once I was warmed up, I headed to the sauna. It fit around 30 people and was arranged in five tiers. Sitting at the top, I could feel a powerful, enveloping heat. The humidity was remarkably high, and the room was filled with the scent of pine aroma. It smelled so good I never wanted it to end. The size of the room, the heat, the fragrance, the humidity — every element was spot on, ticking every box for what makes a great sauna. The automatic löyly every 10 minutes was a wonderful touch too: it kept the humidity consistently high and delivered a fresh hit of pine aroma each time. Absolutely excellent. After the sauna, I moved to the cold plunge. What kind of refreshment would this award-winning water deliver? There were two options: 12°C and 16°C. I started with the 16°C bath. Sure enough, I could feel that distinctive, high-quality-water refreshment — the kind you only get with truly clean water. I've experienced exceptional cold plunge baths all over Japan, and Spadium Japon has earned its place among them. A top-tier cold plunge is a completely different experience from one filled with ordinary tap water. It's like submerging yourself in mint water — a cool, tingling sensation on the skin that lingers long after you step out. Humans are animals after all; our bodies respond naturally to quality water. Next came the outdoor cool-down. The open-air bath area at Spadium Japon had a wonderful atmosphere, and the weather that day was gorgeous. Sitting in a reclining chair soaking up the sun, I drifted in and out of consciousness more than once. Afterward I kept cycling through the sauna and cold plunge in a kind of meditative trance, and by the time I came to my senses, I'd completed five sets. The quality of every single element — the hot spring, the sauna, the cold plunge, the outdoor bath — was exceptional. I finally understood why people are willing to stand in that line.