The Azusa is a limited express service operated by the East Japan Railway Company, which mainly run between Shinjuku and Matsumoto via the Chūō Main Line and Shinonoi Line. The name Azusa is taken from the Azusa River in Matsumoto, Nagano. On the Chūō Main Line, limited express Kaiji also runs between Tokyo / Shinjuku, and Kōfu / Ryūō.