Yumi Care and Storage: Protecting the Bow’s Nari, by Material – Senpodo

When people think of looking after a bow, they think of wiping it down. That is part of it, but it is not the point. The real job of yumi care is to protect the bow’s nari (成り): the overall curve that gives a particular bow its draw and its shooting character. Lose the nari, and no amount of polishing helps.

This page explains what the nari is, how care differs between glass, carbon and bamboo bows, how to stand and store a yumi, how climate affects it, and how to look after the grip.

The short version

The two goals: keep the nari intact, and avoid direct sun, heat, and extremes of humidity and dryness.
Whether to unstring after practice depends on the material. Glass and carbon bows tolerate staying strung relatively well. Bamboo bows are normally unstrung after use so they can recover their reverse curve.
Store the bow upright in a bow stand (yumi-tate). Leaning it casually against a wall, or laying it across things, can pull the curve to one side over time.
The grip leather (nigiri-kawa) is a consumable. Rewrap it when it wears, slips or turns sticky.
Know what your bow is made of first. Everything else follows from that.

What the nari is, and why it is the centre of bow care

An unstrung yumi bends the “wrong” way, away from the archer. This is the urazori (裏反り), the reverse curve. Stringing the bow pulls it up into its working shape. The whole profile, and the way the limbs balance against each other, is called the nari.

When the nari drifts, the upper and lower limbs stop sharing the load evenly and arrow flight becomes less consistent. Every habit in this guide, how you stand the bow, whether you unstring it, where you keep it, is really nari management.

Care by material

Yumi come in three broad materials: glass (fiberglass), carbon, and bamboo. If you have not chosen yet, Bamboo or Synthetic Yumi? covers the decision, including the maintenance burden.

Glass and carbon bows

Synthetic bows are relatively resistant to climate change and easy to look after. They are generally considered fine without being unstrung after every session, which is why clubs and dojo use them daily.

“Durable” does not mean “no care”, though. Direct sunlight, a closed room in summer, or a car interior can get hot enough to raise concerns about deformation and about the bonded joints. After practice, wipe sweat and hand oil off with a dry cloth and keep the bow somewhere cool.

Bamboo bows

A bamboo yumi is a natural material and responds to humidity, dryness and temperature. Expect more work than a synthetic bow:

Unstring or slacken it after use so it can recover its urazori. Leaving a bamboo bow strung for long periods can tire the nari.
Check the nari and the rattan bindings (tō, 籐) regularly. The tō are the wrapped reinforcements along the bow.
Follow your instructor’s method for unstringing and restringing. Procedures differ between schools (ryū-ha) and teachers.

A bamboo bow asks more of you, but looked after well it can be used for a very long time.

How to stand and store a yumi

The rule behind every point here: do not leave uneven force on the bow for long periods.

Use a bow stand (yumi-tate) and keep the bow upright. A bow leaned at an angle against a wall slowly takes a bias under its own weight.
Do not lay it flat on the floor or bridge it across objects. Weight concentrated at one point can change the curve.
If you keep it strung, keep it close to vertical rather than slumped sideways.
Choose a stable spot. A bow that falls over can break.

In a crowded club bow rack it is tempting to prop the bow anywhere. Giving your bow a fixed place reduces both nari damage and breakage.

Temperature and humidity

Bows react to temperature and humidity, bamboo most of all: humidity risks mould and a shifting nari, and over-drying risks cracks.

Avoid direct sun, heaters, and hot windowsides.
Watch out for humid summers and very dry winters, and avoid places where conditions change sharply.
Do not seal a damp bow in its bag (yumi-bukuro). Moisture trapped inside does damage. Let it dry first.
Check it occasionally during long breaks from practice.

Specific temperature and humidity targets circulate, but conditions vary so much by region and home that we do not give fixed numbers. The practical rule: a room that is comfortable for people and does not swing between extremes.

For archers outside Japan, this is where bow care gets serious. A bow that is stable in a Japanese dojo may face a dry winter with central heating, or a humid coastal summer. That matters little for a glass bow and a great deal for bamboo. If you own a bamboo bow abroad and nobody near you knows how to look after one, take that into account before buying.

The grip leather (nigiri-kawa)

The nigiri-kawa (握り革) is the leather wrapped around the grip. It gives traction and a consistent hold, and it wears: it gets polished smooth, sticky with sweat, or starts to lift at the edges.

Wipe surface dirt with a dry cloth, and wipe off sweat soon after practice.
Rewrap it when it slips, lifts, or feels different in the hand.
You can learn to rewrap it yourself, but have an instructor or experienced archer show you the first time.

There is no fixed replacement interval; it depends entirely on how much you shoot. “When it starts to feel wrong” is the practical test. Replacement grip leather is inexpensive: at one Tokyo kyudo equipment shop it costs 660 to 1,650 yen depending on the material (tax included; Koyama Kyugu official online shop, checked 6 October 2026, https://www.koyama-kyugu.com/products/list?category_id=17).

Daily habits that make a bow last

Wipe off sweat and oil after practice.
Store it upright in a bow stand.
Keep it out of direct sun, heat, and extremes of humidity or dryness.
Decide by material whether to unstring or slacken it.
Check the grip leather and the tō from time to time.

The same habits apply when you move up in draw weight to a new bow; see Kyudo Bow Strength (Kyuryoku).

FAQ

Should I unstring my bow after every practice? It depends on the material. Glass and carbon bows are generally fine left strung, and many archers do not unstring them each time. Bamboo bows are usually unstrung after use so the urazori can recover. Check what your bow is made of and follow your school’s or instructor’s practice.

Is it bad to lean my bow against a wall? Leaning it casually at an angle can slowly bias the nari under the bow’s own weight. Use a bow stand and keep the bow as close to vertical as possible; this also prevents it falling and breaking.

What matters most when storing a bamboo bow? Humidity, dryness and temperature change. Avoid direct sun, heaters and damp places, unstring it after use, and check the tō and the nari from time to time.

How often should I rewrap the grip? There is no fixed interval. Rewrap it when it becomes slippery, starts to lift, or feels different.

I will not be shooting for a while. What should I do? Wipe off sweat and dirt, let any moisture dry before bagging it, and store it upright away from sun and heat. Take it out occasionally to check the nari and the surface.

This page summarises general care practice for Japanese bows (checked October 2026). Procedures for stringing and unstringing, especially for bamboo bows, vary between schools and instructors; follow theirs. We are an independent guide. We do not repair equipment, but we can order it from makers and shops in Japan for you — see Ordering from overseas.