Night on the Galactic Railroad

Manga / anime from the 80s Giovanni is a boy from a poor family, who works delivering papers to feed his sick mother (who has contracted an unnamed disease). Due to his adult responsibilities, Giovanni never has any free time and is ridiculed by his peers, making him something of a social outcast. His kindly friend, Campanella, is the only one (apart from his teacher, mother and sister, the latter two of whom are never actually seen) who cares for him. What is true happiness?