is a Japanese commuter railway and keiretsu holding company in the Greater Tokyo Area as well as an intercity and regional operator in the Kantō region. Excluding the Japan Railways Group companies, Tobu's rail system is the second longest in Japan after Kintetsu. It serves large portions of Saitama Prefecture, Gunma Prefecture and Tochigi Prefecture, as well as northern Tokyo and western Chiba Prefecture. The Tobu Railway Company is listed in the First Section of the Tokyo Stock Exchange and is a constituent of the Nikkei 225 index. The Tobu corporate group is also engaged in road transportation (bus/taxi), real estate, and retail. It is the owner of the Tokyo Skytree, the tallest tower in the world. The company is a member of the Fuyo Group keiretsu. The name "Tobu" is formed from the kanji for east (東) and Musashi (武蔵), the initial area served. History Tobu is one of the oldest railway companies in Japan. It was established in November 1897 and began operation between Kita-Senju and Kuki in August 1899. The Tojo Railway was founded in 1911 as a separate company, but shared its president and head office with Tobu. In 1905, Nezu Kaichirō became the president of Tobu Railway and successfully helped to grow the company to one of the largest private rail operators in the Kanto region. Tobu was the first railway in the Kanto region to adopt quadruple tracks, on the Kita-Senju to Takenotsuka sector in 1974. The Tobu Dobutsu Koen (Tobu Animal Park) opened in 1981. Railway network Tobu has two isolated networks which are connected by the Chichibu Railway for ferrying of its rolling stock. The Tobu Main Line network has a tree topology starting at in Tokyo, with the Isesaki line as the trunk, and the Tobu Kameido Line, Daishi Line, Tobu Urban Park Line, Tobu Sano Line, Koizumi Line, Tōbu Kiryū Line, and Nikkō Line forming the branches, with further branches into the Tobu Utsunomiya Line and Tobu Kinugawa Lines. It offers surcharged, seat-reserved limited express services from Tokyo to Nikkō and Kinugawa. The Tojo Line runs northwest from in Tokyo to central and western Saitama Prefecture. A branch, the Ogose Line, runs to from . Tobu's terminals in Tokyo are at (Main Line express services), (most other Main Line services) and (Tojo Line). The Skytree and Isesaki Lines interoperate with the Tokyo Metro Hibiya Line, Tokyo Metro Hanzomon Line and