Hijiki algae are mainly found along the coasts of East Asia, especially in the temperate marine regions of Japan, South Korea and China. They grow on rocky substrates in the intertidal zone to a depth of about 6 metres. The most important harvesting areas are the Japanese prefectures of Mie and Wakayama, the south coast of the Korean Peninsula and the coastal region around Zhejiang in China.

Hijiki algae are deep brown to black, with a bushy, branched growth habit. The plant is about 20–50 cm long, with narrow, firm branches that curl in the current. Its structure is firm and resistant to currents and dryness at low tide.

Hijiki is harvested exclusively in the wild, mostly by hand at low tide or with simple tools from boats. After harvesting, the material is thoroughly washed, sorted and cooked. It is then dried, usually in the sun or in hot air dryers. The dried product is divided into leaves or short, cut pieces and packaged.