On Friday night I finished work at 18:00 → took a 20:00 flight → arrived at Haneda Airport at 21:30. It felt like a seamless sauna → cold plunge → open-air rest routine. I was traveling from Haneda Airport toward Oimachi Station, and even though it was late (around 22:00), the trains were extremely crowded. As someone living a quiet, retired life in the countryside, 22:00 is usually when I’m already asleep, but in Tokyo it felt like the night was just beginning. Feeling both excited and a little intimidated, I transferred at Shinagawa to the Keihin-Tohoku Line and arrived at Oimachi Station. I checked into a nearby business hotel, stayed in the room for about a minute, and headed straight to my destination: Stay-Over Sauna Shop Shinagawa Sauna (Tomareru Saunaya-san Shinagawa Sauna). It’s a new facility that opened in June 2024 and wasn’t around when I lived in Tokyo. It’s been talked about among sauna lovers nationwide and even featured in sauna magazines, so I’d been wanting to visit for a while. Walking toward the facility, I spotted a sign that said SAUNA. I passed through the noren, checked in, and headed to the main bathing area with the saunas. The site footprint is small, so the changing area felt a bit cramped, but the saunas themselves were unquestionably high quality. The moment I entered the main bath area, the world changed. The dimly lit bathroom centers around three cold plunge baths: Little Mermaid at 19°C, Single at 8°C, and Fukan-yu, a 30°C tepid bath. Two sauna rooms, ZEN and KUU, surround those cold plunges. Climbing the stairs to the rooftop revealed a space truly worthy of the name Oasis. A warm bathtub sits in the center, surrounded by over 20 rest chairs. There are chairs for lying down and for sitting, so you can choose whatever suits you. Above all, the atmosphere is wonderful: the ceiling and walls are covered in plants, making you feel like you’re doing an open-air rest in a tropical forest. Many people were relaxing outside, and they all seemed utterly captivated by the space. After a quick look around, I started my sauna session. Shinagawa Sauna has two saunas. ZEN is designed around the concept of facing oneself and offers self-löyly, while KUU hosts events like aufguss. For the first set I entered ZEN. The room is tea-room themed, so the scent of tea fills the air and the seating is tatami. They even provide partitions for privacy. The concept of confronting yourself is perfectly realized. Sitting on the tatami with my eyes closed and focusing on my breath, I forgot I was in the middle of the city. When I performed self-löyly, steam filled the room with the aroma of tea. Facilities that offer tea löyly are rare nationwide, and I was grateful for this unique experience. After the sauna I chose the 19°C Little Mermaid cold plunge. It sits in the center of the bath area and is entered by climbing a short set of steps, which reminded me of Yurakkusu in Kumamoto. This cold plunge is 140cm deep and intentionally designed for submersion. Many facilities prohibit diving, so I appreciated that this place deliberately allows submersion to satisfy sauna enthusiasts. After cooling my whole body from head to toe, I moved up to the rooftop open-air rest area. The rooftop open-air rest area is truly splendid; looking at the beautiful plants almost made me doze off. A few people were already snoring, and given the oasis-like atmosphere, it was easy to understand why. Even when building a sauna facility within a limited urban space, you can create an experience that feels integrated with nature. I learned that you don’t necessarily need vast wilderness to achieve a similar feeling—by shaping the atmosphere as Shinagawa Sauna did, you can provide comparable experiences. For the second set I went into KUU, where you can enjoy aufguss. The L-shaped benches face two IKI stoves. After warming my body for a while, a staff member entered carrying aromatic water and addressed us: We just did an aufguss a short while ago, but since it’s Friday and late at night, I’d like to fan you until my stamina gives out! I’d never encountered anything like that before—what hospitality. The other guests laughed along. The staff then poured aromatic water onto the sauna stones; the lemongrass scent spread through the room and an intense heat wave hit. The staff’s pride seemed to ride that heat wave, making it feel even hotter. Reaching my limit, I plunged into the cold plunge. Lying back in the rooftop open-air rest area, I felt delighted that the trip had already delivered an amazing experience from the very start. Experiences like the aufguss that night are things you can only get by traveling, and since every facility has a completely different concept and design, each experience becomes deeply etched in your life. Spa and sauna experiences always put you at the center and stimulate both your mind and senses, leaving strong memories. That’s why I can’t stop going on sauna trips. After enjoying the ultimate sauna experience at Shinagawa Sauna, I returned to the hotel past 1:00 a.m. It had been years since I stayed up that late. For someone living a retired life, it was a nice jolt. Sometimes it’s important to break your daily rhythm. Rolling onto the bed with thoughts that justified my late-night adventure, I soon slipped into a deep sleep. Tomorrow I’ll travel to Saitama Prefecture in the morning to visit another top-tier facility.