This is actually a great example of how material concerns influence culture. The differences (including this one) between manga & american comics don’t come from “japanese culture” or whatever, but from the economics of selling anthology magazines vs individual books.
In American comics, stuff runs as individual comic books and then may eventually get collected into trades, if the individual books sell well enough. The books themselves are treated as totally disposable except by would-be collectors. Back-issues are available from the printer for a very short time, and series go on for a long time. Comic readers can’t expect to order the whole run of something, and comic writers therefore need to create comics that encourage but do not depend upon familiarity with previous issues. With this model, it’s easier to turn some profit but it’s harder to get really big: you need a superstar title.
The superstar title will fund the other titles but it won’t drive sales for them particularly, and that’s sort of why we have Marvel and DC and then a million tiny players, and then within DC you have Batman and Superman and a million tiny players. (Marvel sales are driven by the movies now instead of the other way around and they always had a lot of focus on big sprawling interlocking stories involving bit players, but still, circa…
