Dongdaemun Sparex is the best! It's affordable, clean, spacious, and comfortable. The location is also incredibly easy to find. Dongdaemun Design Plaza is right across the street. You can easily find it by taking the elevator down to the third basement floor of the building. They don't provide shampoo, conditioner, body wash, or scrubbing towels, so it's a good idea to bring your own. If you forget, they sell them at the entrance, which is convenient. For women, mugwort steaming is highly recommended! It costs 2,000 yen. It feels incredibly good and makes you sweat a lot. After that, getting a body scrub is the best! On the fourth basement floor, there's also a food court, a jjimjilbang (Korean sauna), and a relaxation area where you can unwind. Going in the morning is recommended as it's less crowded.