noun
midnight express; late-night express
Refers to a train or bus service that runs late at night, typically after regular hours. Often used for special overnight or early-morning services.
深夜急行バスで空港まで行った。
I went to the airport by the late-night express bus.
この路線には深夜急行が走っている。
A midnight express runs on this line.
Compound of 深夜 (shin'ya, 'late night') and 急行 (kyūkō, 'express'). The term is straightforward and modern, with no obscure historical derivation.