Short answer: Kakishibu is the fermented juice of unripe, astringent persimmons. Its tannin dries to a tough, water-resistant film, so for centuries people in Japan brushed it onto paper, wood, cloth and fishing nets, and sake brewers used it to clear their sake. Its use in soap is far more recent. It sits alongside a frank Japanese conversation about kareishu (加齢臭), the smell that can come with age.
What kakishibu is
The name joins two words: kaki, persimmon, and shibu, the dry, mouth-puckering astringency of unripe fruit. The same root gives Japanese the word shibui, which can mean astringent but also describes a quiet, understated kind of good taste.
According to the sake glossary of the Society for Nada Sake Research, kakishibu is made from tannin-rich astringent varieties picked while still green. The fruit is crushed and pressed, the juice ferments for around a month, and it is then heat-treated and aged for months or years. The result is a reddish-brown to almost black liquid (Nada sake glossary, "Shibu"). It also has a distinctive smell of its own, which is worth knowing if you have only met persimmon as a soap ingredient.
The tannin itself is a very large molecule. Japanese chemists showed in the 1970s that it is built from catechin-type units, the same family of plant compounds found in green tea (Matsuo and Ito, 1978, Agricultural and Biological Chemistry). Tannins bind to proteins, which is what causes that puckering feeling in your mouth. As kakishibu dries, it forms a tough film that does not dissolve in water.
A long history in everyday life
Persimmons have been grown in Japan for well over a thousand years; the earliest written record is usually traced to Honzō Wamyō, a dictionary of medicinal substances from 918. Their juice found practical uses early on. Research published by Japan's National Museum of Japanese History describes a simpler kind of lacquerware that appeared in the 11th and 12th centuries, with an undercoat of persimmon tannin mixed with charcoal powder and only about one coat of lacquer on top (Yotsuyanagi, 2018, Bulletin of the National Museum of Japanese History).
The heyday came later. A 2022 feature in Blue Signal, the magazine of West Japan Railway Company, describes roughly 300 years, from the middle of the Edo period until plastics arrived after the Second World War, when kakishibu was part of ordinary life (Blue Signal, vol. 197, in Japanese). People valued it because it kept water out and helped protect materials against rot and insects.
| Where it was used | What it did |
|---|---|
| Paper fans and umbrellas | Strengthened and waterproofed the paper |
| Wrapping paper for parcels | Made paper tougher and more water-resistant |
| Tea chests, tubs and buckets | Protected the wood |
| Fishing nets and lines | Helped natural fibres last longer in water |
| Cloth | Dyed it a warm brown |
| Lacquerware | Formed a simpler undercoat beneath the lacquer |
| Sake brewing | Helped settle out haze to clear the sake |
Stencils for kimono fabric
One of the best-known uses survives today. Ise katagami, the paper stencils used to dye patterns onto kimono fabric, are made in Suzuka in Mie Prefecture. According to Japan's Traditional Craft Industries Promotion Association, three sheets of handmade washi paper are glued together with persimmon tannin, with the grain of each sheet alternating in direction, then smoked, soaked in tannin again and left to mature for one to two years before use. Ise katagami was officially designated a traditional craft in 1983 (Traditional Crafts Aoyama Square, "Ise Katagami").
Tea fields and persimmon trees
In the Yamashiro area south of Kyoto, known for Uji tea, astringent persimmon trees were once planted among the tea fields to help protect them from frost. After the tea harvest, the green persimmons were gathered and pressed for kakishibu. Production carries on there today, though on a small scale: the Blue Signal feature notes that only three companies in Japan now make more than 30 tonnes a year.
Kareishu: how Japan talks about ageing body odour
Japanese has an everyday word for the smell that can come with age: kareishu (加齢臭). Karei means growing older and shū means odour. In the US you might see the same thing called age-related body odor. It is a plain, descriptive term, and Japanese companies such as Shiseido use it openly in research and consumer advice.
Much of the science came from Japan. Shiseido says its researchers identified 2-nonenal in 1999. The study, published in 2001 by a team led from Shiseido's product development centre, analysed the body odour of people aged 26 to 75 and found 2-nonenal, which has a greasy, grassy smell, only in those aged 40 and over (Haze et al., 2001, Journal of Investigative Dermatology). For the science in more detail, see what is nonenal?
What stands out is the tone. A 2014 consumer guide from Shiseido (in Japanese) makes several points:
- Kareishu is often assumed to be a middle-aged man's problem, but it occurs in women and men alike from around the age of 40.
- The smell is often likened to candles or old books.
- It is described as a natural ageing of body odour that happens to everyone, and readers are told not to become overly anxious about it.
- Body odour is framed as a kind of "invisible grooming". Because we get used to our own smell, the guide suggests asking family to check our clothes now and then.
- The advice is practical: bathe or shower to wash away skin oils, wash clothes often, and eat a balanced diet.
That calm, matter-of-fact approach is a useful model wherever you live. Japanese articles often say Shiseido coined the word kareishu itself. We could not confirm that from Shiseido's own published material, so treat it as a popular account rather than an established fact.
From craft material to soap
Persimmon tannin has found newer uses too. The Nada glossary lists cosmetics and deodorants among them, and the Blue Signal feature mentions purified persimmon tannin powder being used as an ingredient in cosmetics and disinfectant products. Persimmon soaps, now sold well beyond Japan, draw on this tradition.
It is worth being clear about what that does and does not mean. Centuries of use on paper, wood and nets show that kakishibu is a remarkable material; they do not show that a persimmon soap works differently on skin from a careful wash with ordinary soap. Good evidence on that question is limited, and we look at it honestly in does persimmon soap work? What any soap can do is help wash away the oily residue that carries the smell.
Tip: Kakishibu sold for dyeing or wood finishing is a craft material, not a skincare product. Don't use it on your skin; choose a soap that is made and labelled for washing.
Frequently asked questions
Is kakishibu the same as persimmon soap?
No. Kakishibu is a fermented persimmon liquid used as a dye, a protective coating and a sake-clearing agent. Persimmon soap is a cosmetic that lists persimmon extract or persimmon tannin among its ingredients.
Does kakishibu smell?
Yes. Fermented kakishibu has a distinctive smell of its own, which is one more reason to keep craft kakishibu for craft projects.
Is kareishu only a problem for men?
No. Shiseido's guide says it occurs in women and men alike from around 40. It suggests the smell may be more noticeable in men partly because men tend to produce more skin oil, and because suits and coats are often worn many times between cleans.
Where does the word kareishu come from?
It combines karei (ageing) and shū (odour). It is widely said to have been coined by Shiseido around the turn of the millennium, but we have not found that confirmed in a primary source.
Can I buy kakishibu outside Japan?
Yes. Textile and craft suppliers sell it, for example as a powder, for dyeing fabric and other craft work. Read the safety information that comes with it, and keep it away from children.