Learning the 500 most common words in Frieren gives 85.9% word coverage but only 38.4% line comprehension. This gap exists because a line requires knowing every word — at 7 words average, 0.859^7 ≈ 35% chance per line. Across eight anime, Serial Experiments Lain needs the fewest words (401) for 50% line understanding, while Jujutsu Kaisen needs 980. At 500 words, line understanding ranges from 32.7% (Jujutsu Kaisen) to 55.9% (Lain).
Over half of missed lines lack just one word (50–64% across shows). Expanding from 500 to 1,000 words adds only 6.5 coverage points but 22.1 line-understanding points, as each new word often completes a line. However, those 1,042 one-word-gap lines in Frieren involve 804 distinct words — no single word unlocks more than four lines.
General Japanese top-2,000 words yield only 23–38% of lines; show-specific top-2,000 reach 74–93%. Lain has under 2,000 unique words total. The data comes from manga-kotoba, with similar patterns in jpdb and jiten.
Source: Hacker News · Summarized by HeadlinesBriefing