Guide
How filler happens: why long anime run out of story
Mochibayo ·
Filler is the part of an anime that its source never had: episodes and whole story arcs written for the anime, with no chapter of the manga behind them. In Japan they are called anime original, or aniori for short. English-speaking fans say filler, because these episodes fill time until there is more story to adapt.
This guide explains why filler happens, the forms it takes, how some famous series dealt with it, and how to decide what to skip. In Mochibayo’s filler guides every episode is marked canon, filler or recap. Those labels come from MyAnimeList, and this guide uses them too.
Why anime runs out of story
Most long anime adapt a manga that is still being written. A weekly manga publishes about one chapter a week, and a weekly anime episode often covers two or three. An anime that airs every week of the year therefore gains on its source week after week, until there is nothing left to adapt.
When that happens, the studio has four ways out: make up new material (filler), slow down so that each episode covers less of the manga, stop and come back once the manga has moved on, or leave the manga behind and tell its own story to its own ending. Long series of the 1990s and 2000s, which held the same weekly time slot all year, often relied on the first two.
The kinds of filler
Filler episodes stand alone: an adventure, a festival, a day of training, and by the end everything is back where it was. Filler arcs are longer stories of several episodes, sometimes dozens, usually placed between two arcs of the manga.
Recap episodes are built mostly from earlier footage, often while a character looks back on what happened. They give viewers a way back into the story, and they give a production that has fallen behind schedule a week to catch up.
Padding hides inside canon episodes: a long recap at the start, extended flashbacks, a fight stretched over more minutes than the manga gave it. An episode like that counts as canon, so no filler list can help you skip it.
Some episodes mix canon scenes with new ones. MyAnimeList labels each episode as a whole, filler or not, and our guides do the same.
Finally, an anime-original ending replaces the manga’s story once the anime has run past it, as the first Fullmetal Alchemist anime did.
How famous series handled it
The facts on each card are as AniList lists them on the day of writing; the filler labels are MyAnimeList’s.
Naruto
TV series · Studio Pierrot · from 3 October 2002 · based on the manga
The classic case. By episode 135, which ends the chase after Sasuke, the anime had adapted the whole first part of the manga. It kept airing anyway: almost every one of the 85 episodes from 136 to the finale at 220 is filler by MyAnimeList’s labels. The story continued in February 2007 as a new series, Naruto Shippuden.
Bleach
TV series · Studio Pierrot · from 5 October 2004 · based on the manga
Bleach ran for 366 episodes, from 2004 to 2012, and filled the gaps between the manga’s arcs with filler arcs of its own. It ended in 2012 while the manga was still being published, and the manga’s final arc reached the screen only a decade later, as Bleach: Thousand-Year Blood War, from October 2022.
One Piece
TV series · Toei Animation · from 20 October 1999 · based on the manga
Still running after more than 1,100 episodes, One Piece has used filler arcs and recaps, but its main way of staying behind the manga has been pacing. At times an episode covered little more than one chapter, which is why some stretches feel slow. Its filler arcs have mostly been short, so for One Piece the pace matters more than the filler.
Fullmetal Alchemist
TV series · bones · from 4 October 2003 · based on the manga
The first anime began in October 2003, when the manga was only two years old. In the course of its 51 episodes it overtook the manga, went its own way and finished a story of its own, which continued in a 2005 film, Conqueror of Shamballa. It is the fourth way out in its purest form: not filler, but a different story.
Fullmetal Alchemist: Brotherhood
TV series · bones · from 5 April 2009 · based on the manga
In 2009 bones adapted the manga again, this time faithfully and from the start. Brotherhood began in April 2009, when the manga was nearing its end, and its last episode aired in July 2010, weeks after the manga’s final chapter. Starting late, or waiting for the source, is the cleanest answer to filler.
Why new series rarely have filler
Most anime today are made in seasons. A season of twelve or thirteen episodes fills one three-month quarter of the TV schedule, a cour, and then the series stops. When the manga has moved far enough ahead, the studio comes back for another season. The wait can be long, but the episodes that do arrive follow the source.
Filler has not disappeared. Series that air all year still face the same arithmetic, and an adaptation that ends before its source sometimes gets an anime-original ending. But for a new seasonal series, the break between seasons has taken the place of the filler arc.
Should you skip filler?
If you watch for the story, yes: the canon episodes do not depend on filler, because the manga they adapt never contained it. Recaps are safe to skip too. On the longest series, skipping saves dozens of hours.
But filler is not always bad. Some filler episodes are fan favourites, and filler arcs give side characters time the manga never did. If you love a series’ world, try a few before you decide.
Every title on Mochibayo with an episode list has a filler guide: each episode marked canon, filler or recap, with the time you save by skipping. Mark what you have watched, turn on “Hide filler and recaps”, and the guide tells you the next canon episode. Each episode also has its own page that answers whether it is filler.
The labels come from MyAnimeList through the Jikan API. MyAnimeList builds its database from its users’ submissions, so the line between canon and filler is sometimes a matter of judgement, especially for mixed episodes.
Think we have labelled an episode wrongly? Write to hello@mochibayo.com and tell us which one.