What is Koso?

KO・SO (酵素)
an enzyme, a ferment

“Koso drink | fermented drink using traditional Japanese methods, rich in prebiotic and probiotics. It is also simply called Koso.”

"Koso" is defined as an enzyme or a ferment in Japanese. Koso drink is a traditional enzyme drink created from vegetables, fruits, and plants, which provides abundant probiotics + prebiotics + postbiotics. Koso is popular among young Japanese women, juice cleansers, and individuals who attempt intermittent fasting. Koso has been a healthy and safe dietary supplement in Japan, dating back about 100 years.


Japan has a long history of making fermented foods, such as miso, soy sauce and sake. Fermented foods are essential ingredients in the dietary habits of Japanese people. In the past, it wasn't easy to locate enough ingredients to sustain a healthy diet due to the lack of nutrient-dense foods. When Koso was created, it provided many different types of essential nutrients, allowing people to improve their quality of life.

Advantages Of R's KOSO

R's KOSO is Japan's best-kept health cleansing secret. R's KOSO contains over 100 different fruits, vegetables, and plant-based ingredients. R's KOSO includes unique ingredients such as seaweeds and mushrooms. Seaweeds are one of nature's best dietary source of iodine, which has been proven to help support the thyroid gland. Plus, seaweed is a little known secret that helps Japanese women maintain such beautiful hair. Mushrooms possess many vital nutrients like β glucans, dietary fiber, mannans, as well as act as prebiotics to stimulate the growth of gut microbiota.


R's KOSO utilizes over ten different yeasts during the one-year fermentation process, including lactic acid bacteria, and koji, which is a Japanese cultural fungus. Additionally, R's KOSO contains probiotics, prebiotics, and postbiotics such as acetic acid. All these essential ingredients help improve gut health, which is closely linked to weight loss, skin health, and mental health. Also, it could be long-term solutions for bloated stomach and constipation.

R's KOSO - Japanese Postbiotic Drink (474ml / 16oz)

*Mix with sparkling water to make a Plum Flavored Soda.

$99.00 (Free Shipping)

$99.00 $74.25 (Free Shipping)


✔   Enhanced gut health

✔   Healthy Weight Digestion

✔   Help with skin trouble

✔   Boost immunity

✔   Mental clarity & Sleep

1bottle is good for

✔   Breakfast Cleanse - 2-4 weeks

✔   1-Day Cleanse - 3-4 times

✔   3-Day Cleanse - 1 program

Trial Pack - 30ml × 5 bottles

It's NOT A SHOT. We recommend mixing with sparkling water.

Limit One per Customer


Trial Pack is good for

✔   Breakfast Cleanse - 1 week

✔   1-Day Cleanse - 1 time

How to make R's KOSO?


Natural 100+ fruits, vegetables, plants including mushrooms and seaweeds. All ingredients are from Japan.


Cut ingredients and put natural sugar in a well-balanced state. The component is extracted as an extract without using any water by osmotic pressure.


Add secret Lactic acid Bacteria, Yeast and, Koji for fermentation. There are many useful microorganisms.


All ingredients are fermented and aged for about 1-year by the cryogenic tank. Our factory has 70 years' experience to make Koso. The product is manufactured to exceptional standards by highly trained professionals. All ingredients comes from Japan.

Science by Dr. Roger

I was able to lose my weight for around 5,6 pounds and clear my stomach. Plus, I didn't feel hungry that much during the process.

Youngrok Kim

The taste is great. It tastes like a sweet Japanese Plum Juice. It is much better than Kombucha. Easy to consume daily.

Samuel M

I’m feeling fantastic— energized and distress-free. KOSO is now officially a part of my self-care regimen.

Bruce Sadia
Yoga Teacher and Integrative Coach

I have found it helpful during my intermittent fasting as well as with my gut support.

Blake Sinclair
Author and Life and Wellness Coach

It changes your body and mental a lot. Even you feel hungry on Day2, it comes OK and you will get to the next stage of your life. I recommend.

Takeshi Homma

You will not find a better drink if you want to achieve your personal weight goals. Tastes good and just the right portion.

Noriya Tarutani
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