The Demon Slayer show has these inscriptions on eyes that mean "upper 6" or "lower 12" etc. I haven't seen these "upper" and "lower" rank words in my studies. And the number symbols are unfamiliar too. It seems Tanjiro says "じょうげんのろく"

The eyes seem to spell out:


Looking at Jisho for that with a space yields a clue. Apparently 陸 is also 6 just like ろく or 六. Even though the main definition is land or shore​.

Luckily 上弦 on jisho fits what I hear as "じょうげん" which means "1st quarter of moon; crescent moon" so I guess that means like a moon rank or something?

Why are these numbers written so differently in demon eyes? Is the literal translation more like "6 of the moon" or is this moon thing a standard ranking system? What's going on?

upper six demon eyes in demon slayer

lower five moon demon eyes

  • 3
    See this regarding the numbers. ja.wikipedia.org/wiki/大字_(数字)
    – Cabbage
    Commented Dec 27, 2021 at 4:32
  • 上弦の月/下弦の月: ja.wikipedia.org/wiki/%E5%BC%A6%E6%9C%88 It doesn't really mean anything complex or profound, as far as I understand the plot. They might as well be 白/黒.
    – Eddie Kal
    Commented Dec 27, 2021 at 5:30
  • JFYI, this upper/lower distinction is unique to this work. There is no such a thing as "upper six" in standard Japanese. 陸 is a rare alternative way of writing 六, but neither is "upper" or "lower".
    – naruto
    Commented Dec 28, 2021 at 6:33
  • Thank you folks. I believe the answer is the combination of your comments. I see it's not possible to author an answer on this because it's marked as a duplicate. I'm not sure if that's the best way to handle this type of question, because it is a more specific question than the more general answers cited. But ok. Thank you for your help! Commented Jan 5, 2022 at 2:01


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