List of through trains in Japan

Japan operates a variety of through-services (直通運転, chokutsu-unten) or nori-ire (乗り入れ) or through trains which are direct seamless connections between rail operators, using leased trackage rights and junctions, to cut cross metropolitan area commutes without having to change trains, wait, figure out connections, or cross platforms/stations. Most of these junctions have been constructed well after the lines have been operating.

Source: Wikipedia — List of through trains in Japan (CC BY-SA 4.0)