The most common complaint about any adaptation is that it changed something. Cut a scene, reordered an arc, gave a line to a different character, dropped a subplot. The complaint is usually delivered as though the change is self-evidently the problem.
It is not, and treating faithfulness as the measure produces some very strange conclusions — including having to defend adaptations that are boring precisely because they refused to change anything.
Faithful to what, exactly
A manga page and an anime episode are not the same instrument. You control the pace of a manga completely: you linger on a panel, flick back three pages, read a double-page spread in whatever order you like. An episode moves at a fixed speed whether you are ready or not.
So a sequence that works on the page can fail on screen for reasons that have nothing to do with the writing. A panel you spent four seconds absorbing becomes a shot that is either too short to register or held so long it drags. Internal monologue that reads naturally in a caption box becomes a character standing motionless while a voice explains their feelings.
Adapting means finding the equivalent effect in a different medium. Sometimes the equivalent effect requires changing what happens.
The one-to-one problem
An adaptation that refuses to cut anything has a recognisable failure mode. Pacing stalls, because manga chapters do not divide evenly into episodes and the material has to be stretched to fit. Scenes that existed to be flipped past become full sequences. You end up with manga panels with voices over them.
The reverse case is worth noticing too. Anime gains things manga cannot have — sound design, voice performance, motion, colour, music timed to a beat. An adaptation that adds nothing is declining to use most of its medium.
Changes that are actually bad
This is not an argument that all changes are fine. There is a real distinction, and it is not about size:
- Changes that break causality — removing the thing that explains why a later event happens, so the story stops making sense on its own terms
- Changes that contradict established character — someone acting in a way the adaptation itself has not set up
- Changes that resolve ambiguity the original deliberately left open, usually by explaining something that worked because it was unexplained
- Changes made to hit an episode count rather than to serve a scene — the compression that flattens a three-episode arc into one
What that leaves
Cutting a subplot is not automatically bad. Reordering events is not automatically bad. Giving a line to a different character is frequently an improvement, because manga can afford a large cast in a way a twelve-episode season cannot.
The question worth asking is whether the adaptation is coherent and effective as a thing in itself — not whether it matches. If you can only explain why a scene works by referring to the manga, the adaptation has failed. If it works for someone who has never read the source, it has succeeded, regardless of how much it moved around.
A better way to say it
"They cut the X arc" is not a criticism, it is a description. "They cut the X arc, so the reveal in episode nine has no setup and lands as a coincidence" is a criticism, and it is one that holds up whether or not the person you are arguing with has read the manga.
That is the version worth putting in a review. It tells the next reader something they can act on, and it does not require them to have read the source to understand what went wrong.