GALAXY EXPRESS 999

One year after the events of the First Cycle, Tetsuro has returned to Earth only to end up chained in his home in Megalopolis. It is then that Maetel appears before him once again, offering him the opportunity to join her on a new journey - one she claims will lead him to his destiny. Note: Started 15 years after the series initially ended serialization. The second cycle makes up volumes 15-21. — Description from AniList community (anilist.co).