Sometimes, as you watch an anime, you come across these episodes that aren’t connected to the main story at all and they aren’t in the manga. So what are they? Filler episodes. The greatest evil in all of anime. The source material for the anime(mostly manga) sometimes runs short, so to wait for the source material to accumulate, filler episodes are made.
They aren’t tied to the main story at all, so most of the time you’ll get something like a standalone episode with dull and annoying new characters that have no significance in the universe of the anime. Well, every now and then you get an actual interesting filler episode, like exploring the past of some interesting and mysterious character or some of his exciting adventures that weren’t covered in the original storyline.
Too bad that most of those are annoying beyond belief, and the good ones are rare and far between. The main offenders here are giants like Naruto Shippuden, Bleach and One Piece. Shippuden is by far the worse, as the manga already ended but the goddamn anime is still continuing. This means that 90% of the episodes don’t have anything to do with the current story of the anime.
They focus on the background story of EVERY CHARACTER THAT’S STILL ALIVE or something stupid like that. Sorry I got carried away, but these fillers episodes are one of the worst things in anime, I mean, I once forgot about Naruto Shippuden’s main story line because this one filler storyline lasted forever.