Green tea finished without the finaling shaping stage, so the leaf stays curled rather than needle-straight. Common in Kyushu, made either steamed or pan-fired. Rounder and milder than sencha.
In more detail
Also called guri-cha. The steamed version is ordinary Japanese processing minus the final shaping; the pan-fired version skips steaming altogether and stops oxidation in a hot pan, much as Chinese green tea does — and accounts for a tiny fraction of Japanese output. Curled leaf takes up more volume for the same weight, so measuring by eye gives a stronger cup than you expect.