-What Are hot springs?

A hot spring is a spring of naturally hot water, typically heated by subterranean volcanic activity. Also its a place where groundwater is heated by energy created by the earth. Like the springs in Warm Springs, Georgia, water from hot springs is said to have many beneficial properties, but springs can also provide spectacular tourist attractions. The definition of a hot spring that people enjoy is a natural bath that the source temperature should be higher than 25℃ / 77℉, or have one of 19 ingredients that qualifies as an “onsen” (although sometimes it’s colder than the above temperature). If it has these qualities, it is named “onsen”.

The hot springs are warm, and although some of the ingredients may sound extreme, such as “sulfur bath”, they are safe, healthy, and relaxing. Because the inside of the earth is a high temperature magma, the temperature rises about 2℃ with every layer of the ground towards the core. In other words, the groundwater discharged by digging the ground about 1000m is hot spring, just as the name implies. For these reasons, hot springs have an image of nature’s blessings, but now that the drilling technology has progressed, even in the center of Tokyo, hot spring area are spreading, one after another. For those living in the downtown area, being able to take a hot spring bath in a familiar place is wonderful in terms of health management, stress relief and so on.

-The Difference Between Onsen and Sento

While the Onsen exist for the pleasure of relaxation and the health benefits of bathing in nutrient-rich water, the Sento are local establishments which serve the far more practical need of daily hygiene. Indeed, the two kanji which make up the word Sento mean “coin” and “hot water”. In other words, you are simply buying hot water heated from the water supply just like you would if you ran a bath at home.


-Top 3 Onsen / Sento in Tokyo (Based on Age Demographics)

20’s – 30’s Age Group

Times SPA RESTA (Sento)

It is located in Ikebukuro area. This is recommended by young woman. Once you step into the facility, the time and space extends as far as one can see. A sweet fragrance hangs in the air while relaxing music is played. The concept is bringing out the beauty of woman and there are several areas such as “jet foam open air bath” which rose flowers float on the bath, “clear mist sauna” (with salt scrub) which you are wrapped by citrus aroma while having a bath in the mist. The whole floor is only for woman and you can stay until the morning. Also there are plenty of amenities such as the face steamer, hair iron which are free rental.


40’s Age Group

Minatoyu (Sento)

It is located in central in Tokyo(Haccho-bori area). It is 5min walking from Hacchobori subway station. The atmosphere of the entrance is traditional Japanese style. There is a wooden shoes locker which is the old-fashioned. On the other hand, inside is very stylish bathes. The main bath is the jacuzzi in the middle. This has an effect on massage.
You can enjoy 2 kinds of sauna as well. The unique one is called “Rocky sauna” which is the Finland style sauna. This place has been for over 100years and historic Sento. It used be called “mini-sento” because there was only 1 bath tab when it was opened.

50’s Age Group

Shimizuyu (Onsen)

It is located in Shinagawa area. 2 different hot springs gush out from underground. Also the price is reasonable as Sento inspire of the natural hot springs. There are “black spring’ and “golden spring’. The black spring gushed out million years ago from 200m deep of the geological formations. The water is very smooth, mineral-rich water. The golden spring gushed out 5million years ago from 1500m deep of the geological formations. This is the deepest hot spring and the first place where received medical-hot spring certification.


-How to Enjoy Onsen and Sento

Onsen has many effects such as easing fatigue and keeping us in good health. The minerals contained in the onsen water are absorbed through our skin into our body and provide many medical benefits. There are different kinds of minerals in the water depending on the onsen, and some of these waters are very unique. Sulfur, green tea, nanobubble, and even chocolate infused water can be enjoyed in different places. Each has a special health benefit and aroma.

We have few basic manners to enjoy onsen:

Wash your body before entering the bath.
To warm the body up, splash hot onsen water with a pail, a practice called “kakeyu”, or “to splash hot water”.
Soak up to your shoulders and relax, but try to avoid submerging the head.
Leave the bath without rinsing your body again to keep the minerals on the skin.
Dry your body before getting back to your locker.

We have few rules you shouldn’t do:

Do not wear anything, such as a swimsuit, in the bathing areas.
Long hair should be tied up so as not to soak in the water.
Patrons with tattoos are not allowed (in most onsen).
Do not soak towels in the bathtub.



The reason why tattoos are not allowed to Onsen came from Edo period. At the time, criminals were marked with tattoos for their crimes. Different tattoos were applied for different crimes, at different parts of the body. Their meaning in society however was always the same: “this person is a menace to society. Beware”. Of course this marked them for everyone to see, which made it difficult for them to receive service in many shops, including onsen, who did not want criminals as guests.

If this wasn’t a bad enough image for tattoos, over the centuries criminal organizations known as “Yakuza” began to use tattoos as a mark of bravery and courage, and also loyalty to their criminal group. Large tattoos meant more loyalty and bravery, and the image stuck. Unfortunately for foreign people, who often get tattoos for the purpose of fashion, the Japanese history and image of tattoos is much more troublesome, and no exceptions are made, no matter what country you are from. It can be seen as “equal rights”, just not in a convenient way for inked tourists looking to soak in a hot tub.

There is some good news, however. Slowly, the image of tattoos is changing, as more and more Japanese people are becoming aware of their international meaning. Full body tattoos are still judged very harshly, but if the tattoos are small and can be covered up with tape, or small black sleeves, sometimes the onsen staff will turn a blind eye… sometimes. It’s still best not to mention your tattoos, and be prepared to be asked to leave a strict establishment. Still, be respectful, cover up, use common sense, and take a bath peacefully and you might be fine.