Kosai can stand for: Hiroki Kosai, 20th-century Japanese astronomer Kosai, Shizuoka, Japan, a city Kōsai, a disciple of Hōnen of the Jōdo Shū Buddhist sect Kosai river, near Kharagpur in the Indian state of West Bengal Count Kosai Uchida (or Uchida Yasuya), 19th-20th-century Japanese statesman and diplomat Wiang Kosai, a national park in the Phrae and Lampang provinces of Thailand Kosai or koose, an African pea fritter See also Kozai (disambiguation)