Hishi (Water Caltrop / Water Chestnut)

Hishi is the fruit of Trapa japonica, an aquatic plant that grows in ponds and slow-flowing waters. The fruit is distinctive: a hard black-brown shell with two horn-like protrusions (giving it the alternative English name 'water caltrop' — caltrop being a four-pronged spike), with a starchy white interior similar in texture to chestnut.

Production: Saga Prefecture (notably Kanzaki area) is the established modern production region. Small artisanal production exists elsewhere in Western Japan and Kyushu. Total annual production is small.

Nutritionally, boiled hishi per 100g provides approximately 88 kcal, 2.5g protein, 0.4g fat, 21.4g carbohydrates with 2.5g dietary fiber. The starchy texture and mild sweet flavor are distinctive.

Boiled hishi-no-mi snack — traditional autumn delicacy in Kyushu and Western Japan, eaten boiled in salted water (similar to peanut snack culture).

Saga regional cuisine specialty — featured in Saga regional cooking and autumn festivals.

Heritage retail — vacuum-pack and fresh autumn retail in Saga area and Western Japan tourism.

For OEM: vacuum-pack pre-cooked hishi retail (autumn seasonal), Saga regional gift retail OEM, and heritage cultural cuisine specialty product collaboration.

Standard food labeling. Saga-hishi regional naming is established but not formally GI-registered.

Hishi is not a designated allergen.