Inspired by comments from 10 Most Rewatchable Shonen Anime Series, Ranked
Here are a few examples that I know of:
| title | expected | actual |
|---|---|---|
| Frieren | non-shounen (seinen?) | shounen |
| Attack on Titan | seinen | shounen |
| The Apothecary Diaries | shoujo | seinen |
| Umamusume: Cinderella Gray | shounen | seinen |
| 100 Girlfriends | shounen | seinen |
What are other instances of misidentified demographic you have seen?
Quick and dirty definitions of anime demographics:
- shoujo - girls
- shounen - boys
- josei - ladies
- seinen - men


Six of one, half a dozen of the other. It’s like the fact that you cannot create a category that includes all “fish” that doesn’t also include humans (or, if you want to exclude humans by way of things like body plan or living on land, then you have to include cetaceans and start excluding things like lungfish).
To use your example, most people would probably say there are actually pretty clear expectations of tone & pacing between “a Netflix show” vs. “an HBO show” vs. “a syndicated television show (from before streaming services)” despite them all being the same on the surface.