Halocynthia roretzi is a species of edible sea squirt (class Ascidiacea) in the family Pyuridae, native to the cold and temperate coastal waters of the northwest Pacific, especially around Japan and the Korean Peninsula. It is widely consumed in Japan and Korea and is particularly associated with the Sanriku coast and other northern Japanese fisheries. The genus name Halocynthia combines Greek halos (“sea” or “salt”) with cynthia, a classical name used in zoological taxonomy, while the species epithet roretzi honors the German zoologist Carl Roretz, who conducted marine research in Japan in the nineteenth century. Halocynthia roretzi is a sessile marine invertebrate that attaches to rocks or aquaculture ropes and filters seawater to feed on plankton and suspended particles. Its tough, reddish, spiny outer tunic encloses a soft, orange internal body. In Japanese it is known as hoya (ホヤ) and in Korean as meongge (멍게).

Halocynthia roretzi has been harvested traditionally from wild populations and is now extensively cultivated through marine aquaculture, particularly in Miyagi Prefecture in Japan and along the southern coast of Korea. Its flavor is distinctive, often described as briny, iodine-rich, slightly bitter, and umami-forward, reflecting its marine metabolites and free amino acid content. Halocynthia roretzi is typically consumed raw or lightly dressed. In Japanese cuisine it is served as sliced fresh hoya, sometimes with vinegar or citrus, and may appear in sushi or sashimi assortments. In Korea it is commonly eaten raw with chili paste or incorporated into rice dishes.

The edible tissues are rich in free amino acids such as taurine, glycine, and alanine, contributing to its characteristic taste. Bioactive compounds identified in this species include halocyntin and related peptides, carotenoids, and various nitrogenous metabolites, some of which have shown antimicrobial or cytotoxic activity in experimental settings. While generally safe as a traditional food, its strong flavor profile limits its culinary use to acquired tastes and regional specialties.