The koma is a small removable bridge that sits between the strings and the skin. It costs a fraction of the instrument, it is not glued to anything, and it changes the sound more than almost any other single part you can swap. Across every genre, the entire useful range spans about 3.3 millimetres of height.
Height by genre
Heights are given in bu and rin. Millimetre equivalents below are converted at 1 bu = 3.03 mm, 1 rin = 0.303 mm.
| Genre | Height | Approx. |
|---|---|---|
| Nagauta | 3 bu 3 rin – 3 bu 6 rin | 10.0 – 10.9 mm |
| Kouta / Hauta | 3 bu 3 rin – 3 bu 5 rin | 10.0 – 10.6 mm |
| Jiuta / Minyo | 2 bu 8 rin – 3 bu 3 rin | 8.5 – 10.0 mm |
| Tsugaru | 2 bu 5 rin – 2 bu 8 rin | 7.6 – 8.5 mm |
Tsugaru sits lowest and nagauta highest — the opposite of what people assume from the fact that Tsugaru is the loudest style. Height is not volume.
What height, weight and contact area actually do
- A taller koma — the strings resonate better
- A lower koma — easier to play, and easier to get speed
- A heavier koma — resonates less
- A wider contact area with the skin — more resonance
These pull against each other, which is the point. A koma is not upgraded; it is traded off. Tsugaru players run low bridges because the style demands speed, and accept the resonance cost.
Materials
Koma are made from several materials, among them bamboo, water buffalo horn, bone (shari), ivory and plastic, plus shinobi-koma — muted bridges used for quiet practice.
Two practical notes for buyers outside Japan. First, ivory raises import questions; if you are ordering internationally, ask what the koma is made of before it ships. Second, the muted practice koma is the cheapest way to make a shamisen apartment-friendly — it is worth buying at the same time as the instrument, not after your neighbours complain.
Why this is the part to experiment with
Everything else on a shamisen is either fixed, expensive, or requires a craftsman. The koma is none of those: it lifts out, costs little, and reverses instantly. If your instrument sounds wrong and you cannot say why, this is the cheapest variable to move — before changing strings, and long before touching the skin.
Ask your teacher for the height they expect before ordering. Genre gives the range; the teacher gives the number.
Sources. Genre heights in bu/rin, the koma materials including shinobi-koma, and the effects of height, weight and contact area on resonance: shamisen.ne.jp. Millimetre figures are our conversion, not quoted from the source. Checked 2026-08-18. We do not sell koma — confirm the height with your teacher, who is choosing for your instrument and your playing.