Keio sets about a bus enterprise in early stages of Shōwa period again.

Banzai Jidōsha Co.(万歳自動車) which operated around the bus from the end of Taishō period changed the company name to the Kōshū Kaidō Noriai Jidōsha Co.(甲州街道乗合自動車) in July, 1924, and the route was extended to Tama-mura Tokyo city-owned park cemetery (present Tama Cemetery) through Karasuyama and Chofu.

Furthermore, the Keio acquired Kōshū Kaidō Noriai Jidōsha in 1937, and absorbed enterprise all.

Head Office of Keio Dentetsu Bus and its subsidiaries - 2-22, Harumichō, Fuchu, Tokyo, Japan The vehicles introduced from four manufacturers, Hino, Isuzu, Mitsubishi Fuso and Nissan Diesel, are held into the Keio Dentetsu Bus Group.

The reason is that the one-step vehicles with narrow width and long body (Nissan Diesel JP) were purchased in lump sum from Nissan Diesel in advancing low floor-ization of vehicles in the mid-1990s.