Drifting Train 000

(from ebookjapan):

Dai Oyama, a struggling student attending junior high school while working part-time, mistakenly boards a train that is not on the timetable and should not exist. The name of the train is the "Drifting Main Line 000".

Oyama, who has obtained a commuter pass for the infinite section of the 000 that travels through time, sets off on a journey through time and space, guided by the mysterious beauty, Mavis! Upon alighting at a station named Nishimujidani (西無時谷), Oyama sees a city where time has been suspended in the pursuit of eternal peace and happiness...

A space-time romance epic by Leiji Matsumoto!