GEOS (株式会社ジオス, Kabushiki Gaisha Jiosu) was one of the Big Four private eikaiwa, or English conversation teaching companies, in Japan. Its extensive network of overseas schools made it the world's largest language school chain. The firm went into bankruptcy in Japan on 20 April 2010. Its headquarters were in the Shin Osaki Kangyo Building (新大崎勧業ビルディング, Shin Ōsaki Kangyō Birudingu) in Shinagawa, Tokyo.