The Keisei Main Line 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 the early 20th century, the line has been serving 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.

Narita International Airport , also known as Tokyo-Narita International Airport, formerly and originally known as New Tokyo International Airport , is one of two international airports serving the Greater Tokyo Area, the other one being Haneda Airport (HND). It is about 60 kilometers (37 mi) east of central Tokyo in Narita, Chiba. The facility since July 2019, covers 1,137 hectares of land and there are future plans to expand to nearly 1,200 ha.