The best and longest anime series are broken up into story arcs. Each arc has its own narrative, prominent characters, stakes, and most of all, plot developments. Any great anime story arc will make the most of that formula, such as introducing cool new characters, killing off other characters, expanding upon the combat system, and much more. Some story arcs move the story forward in relatively predictable ways, but other arcs might totally shake up the status quo with shocking developments of all kinds.
Source：https://www.cbr.com/iconic-anime-arcs-that-changed-everything/
