Anime Semantle

The previous article measured difficulty across 17 genres. The result ran from 0.679 (sports) to 0.781 (supernatural) — a range of 0.102.

But the MAL data carries a much finer axis: 49 theme tags. School, historical, mecha, music, time travel — tags describing what the story is about rather than what shelf it sits on. Re-measured on that axis, the range widens to 0.210, more than double.

1. Same measurement, finer axis

The method matches the earlier article. For each title we took the similarity of its nearest neighbor with its own franchise excluded, then grouped those numbers by tag. Lower means titles carrying that tag are islands in the pool.

Theme tags exist on 675 of the 800 titles (84%). Tags with fewer than 10 titles are dropped, leaving 34, sorted hardest first.

2. The hard end

CGDCT (75%) and Music (57%) also stand out. Both feel like they should cluster and do not. Slice-of-life shows have little plot to put in a synopsis, and music shows split between bands, piano, jazz and idols — different stories entirely.

3. The easy end

Vampire at 0.853 leads all 34 tags by a clear margin. Only 16 titles carry it, and they are all each other's neighbors — the premise itself nearly dictates the story: humans and bloodsuckers, night, blood, immortality.

Reincarnation (4%) and Isekai (6%) behave the same way. Once the tag applies, the opening sentence of the synopsis is nearly identical.

4. Big umbrellas and the holes inside them

This is the most useful finding here. Broad tags are easy; the narrow tags inside them are hard.

"School anime" is 152 titles packed together, easy to land. Narrow to the ones about a music club and those 40 are scattered. That is why you stall at 0.75 — you have the umbrella and have fallen into a hole inside it.

5. How to use this in the game

• Stuck around 0.65 repeatedly? Suspect the subject matter. It may be a tag like racing, music or slice-of-life where same-subject titles do not cluster. The fix is not a different instance of the subject — it is dropping the subject and switching to tone.
• Seeing 0.85 means the premise is distinctive. Likely something like vampire or magical girl that dictates structure. A few more same-premise titles usually finish it.
• Landed an umbrella? Search inside it. If school or historical stalls at 0.75, break in via music, organized crime, club activities.
• 16% of titles carry no theme tag. Only 675 of 800 are covered, so some days this table will not explain what you are seeing.

6. Limits

Medians on small tags wobble. Vampire (16), Mahou Shoujo (11) and Racing (13) are small enough that a few titles could reorder them — which is why the counts are printed alongside.

These values are also measured only within the 800-title answer pool. A close relative outside the pool does not register.

Theme tags do feed the similarity calculation: the structural text includes tags alongside title and series name, and that structural text is 70% of the score. The reasoning is on the about page.

Further reading

Which Genres Are Hardest runs the same measurement over 17 genres, and Guessing Shounen Because It Feels Shounen runs it over the shounen / seinen / shoujo demographics. When to Guess a Character and Ratings Are Not a Clue come from the same data. Each day's answer and its nearest neighbors accumulate in the past answers archive.