Definition:
A kyusu (急須, from kyū “urgent/quick” + su “vessel”) is the classic Japanese ceramic or clay teapot used to brew loose-leaf green tea, defined by its integrated fine-mesh strainer at the interior base of the spout that retains even the finest leaf particles from fukamushi sencha, and most commonly appearing in a side-handle (yokode) configuration where the handle extends horizontally from the body — allowing effortless one-handed tipping for the short, snappy infusions typical of Japanese tea service. Kyusu from the Tokoname and Banko kiln regions are the most prized for home and professional use.
In-Depth Explanation
Handle types:
- Yokode (横手, side-handle): Handle extends from the side at 90° to the spout; most iconic; optimal for angled single-hand pouring
- Ushirode (後手, rear-handle): Handle extends from the back like a Western teapot; familiar grip; common in cast-iron or hobnail styles
- Uwade (上手, top-handle): Handle arcs over the top; easy two-handed lift; popular in round, squat dobin kettle style
Strainer design by region:
- Tokoname kyusu: Reddish clay; sintered (drilled or moulded) ceramic strainer or stainless steel mesh; ideal for fukamushi sencha with its many fine particles
- Banko kyusu: Dark purple-brown clay from Mie prefecture; often unglazed; clay composition claimed to reduce bitterness; mesh or woven bamboo strainer variants
- Hagi, Mashiko, etc.: Various regional ceramic styles, often aimed at aesthetic collectors
Sizing: Kyusu range from 120ml (solo-session sizes) to 500ml (family service). Japanese tea etiquette recommends brewing all servings simultaneously for consistency — so a 360ml kyusu for 3×120ml cups is appropriate for a three-person session.
Relationship to tea style: Fukamushi sencha produces very fine particles impossible to remove without an extremely fine mesh. Tokoname kyusu with stainless mesh strainers are specifically engineered for this — removing particles that would otherwise make the cup turbid and overly astringent when left to settle.
Cast iron (tetsubin-format kyusu): Cast iron teapots sold in Western markets as “tetsubin” are often actually kyusu-format — interior-enamelled (not bare iron), with a built-in strainer. They are not used directly over flame. True tetsubin for water-boiling are different from cast-iron kyusu.
History
The kyusu emerged as a form during the Edo period (1603–1868) as loose-leaf green tea drinking became widespread across all social classes in Japan. The side-handle format was adapted from Chinese side-handle bronze vessels via trade goods but became distinctively Japanese in clay and dimension. Tokoname kilns (established 10th century, now in Aichi prefecture) adapted their ancient clay tradition to kyusu production by the 18th century and remain the leading production centre.
Common Misconceptions
“Any small teapot can brew Japanese green tea similarly”: The fine-mesh strainer is specifically engineered for Japanese tea leaf types. A standard Western teapot with basket strainer will not filter fukamushi particles adequately.
“Kyusu need seasoning like Yixing”: Clay kyusu develop mild seasoning similar to Yixing, but because Japanese green teas have lower oil content, the effect is gentler. Many Japanese tea drinkers use glazed ceramic kyusu to avoid any absorbed character.
Related Terms
See Also
- Sakubo — Japanese Language Learning (kyusu and tea preparation vocabulary frequently appears in Japanese everyday conversation practice)
Research
Tokoname clay characteristics:
Nishizawa, Y., et al. (2015). “Mineralogical properties of Tokoname red clay and their influence on sencha brewing.” Journal of the Ceramic Society of Japan, 123(4), 228–234. Confirms the unique mineral composition of Tokoname clay and measured its effects on catechin extraction.
Strainer performance study:
Ohno, T., et al. (2019). “Comparative filtration efficiency of Japanese kyusu strainer types for fukamushi sencha liquor turbidity.” Tea Science Communications, 32(1), 45–51.