The Keisei Main Line (京成本線, Keisei Honsen) is a railway line of Japanese private railway company Keisei Electric Railway connecting Tokyo and Narita, Japan. It is the main line of Keisei's railway network.Built as an interurban between Tokyo and Narita in early 20th century, the line has served as a main access route to Narita International Airport since 1978. It also serves major cities along the line such as Funabashi, Narashino, and Sakura. In 2010, the Narita Sky Access opened as a bypass of the line, reducing the role of the main line in the airport access.