"Haguro-so" (Peristrophe japonica) belongs to Acanthaceae (theRuellia family). It is a perennial herb that is distributed westward from Kanto district of Honshu to Shikoku, Kyushu of Japan, the Korean Peninsula, central China and Taiwan. This herb grows in mountainous tree-shaded areas, and can reach 20-50 cm in height. The leaves are ovate-oblong to lanceolate and arranged in opposite. The peduncles are borne on the terminal branches and axils, and the magenta flowers with leafy bracts bloom in September and October. The corolla are two labiate with two stamens.