Makers · 作家 · Tokoname
Juko
樹晃Born in Tokoname to Koyo, he took an unusual route back to the family kiln — a postgraduate degree in agriculture first, then the wheel. He now works as the fourth generation of Koyo Toen.
At a glance
Drawn from the standard Japanese survey of bonsai ware. Where the record is unclear, we leave it out.
- Art name
- Juko 樹晃
- Real name
- Kuniaki Aiba 相羽久仁晃
- Region
- Tokoname, Aichi 常滑
- Father
- Koyo 鴻陽
- Studied
- Graduate school of agriculture, Shizuoka University
- Trained
- Tokoname municipal ceramic institute — wheel work
- Position
- Fourth generation, Koyo Toen
- Known for
- Glazed hand-built and slab-built work
01 · 経路 The route in
Agriculture first, then the wheel
Potters' sons usually learn at the family bench. Juko went a longer way round: a graduate degree in agriculture at Shizuoka University, then formal training in wheel work at Tokoname's municipal ceramic institute, and only then the kiln he grew up in.
It shows in the work. His strengths are the slower, more deliberate methods — hand-building (tebineri) and slab-building (tatara) — carrying glaze.
02 · 家伝 The family green
A glaze handed down
The most telling piece in the record is a hexagonal pot with cusped-window panels, glazed in green. The survey describes the glaze with a specific phrase: 家伝の緑釉 — the family's green.
That single phrase sets a line running. His father's green is described as recalling Tofukuji's; that green is now inherited rather than reinvented. Three hands, one colour, across most of a century.
“Three hands, one colour.”
03 · 落款 The seals
One mark
Juko signs with a single upright seal reading his art name. Where a pot carries the kiln name as well, see Koyo.
| Mark | Reading | Note |
|---|---|---|
| 樹晃 | Juko — upright seal | His art name. Read ju-kō. |
Photographs of these marks on pots from our own stock will be added here. A mark in the hand rarely looks like a printed plate — clay, glaze pooling and wear all change it.
04 · 代表作 Documented works
Pieces recorded in the literature
Not for sale — the reference pieces published in the standard Japanese survey.
| Work | Size (cm) |
|---|---|
| Unglazed cut-corner rectangle, outer rim — classical Shokodo form | — |
| Keiketsu-glazed rectangle — copper in the glaze, part turned green in the kiln | — |
| Green-glazed hexagon, outer rim — the family green | — |
05 · 展開 Widening out
Pots, and then some
Alongside bonsai ware he makes pieces built for Western rooms, and has widened out into unglazed pots, flower vessels and water trays, tableware, interior pieces and one-off teapots.
The survey's note on his unglazed work is worth keeping: a maker assumed to be a glaze man, it says, turns out to have a sure hand in bare clay as well.
06 · 用語 Glossary
The words on the label
- 手びねり tebineri
- Hand-building — forming by hand without the wheel.
- タタラ tatara
- Slab-building — construction from rolled sheets of clay.
- 家伝 kaden
- Handed down within a family.
- 鶏血釉 keiketsu-yū
- “Cockerel-blood” glaze — a deep red.
- 焼締 yakishime
- Unglazed high-fired stoneware.
- 火燈窓 katō-mado
- The cusped “flame window” outline, borrowed from temple architecture.
Available
Juko pots in the collection
We handle Juko from time to time. Each pot is 一点物 ittenmono — one of one — and ships worldwide from Tokyo.
Sources
盆器大図鑑【上巻】 Bonki Daizukan, Vol. 1, p. 177. Checked against pots handled by YAKUMO JAPAN. Last verified 18 July 2026.
Where the record is unclear we say so rather than guess.