I have heard a Japanese teacher explain how long vowels should be pronounced and how they should be written when using hiragana. That's what I saw on the whiteboard:

がっこう - gakkoo, (not gakkou)

Is it correct? I understand that the sound is pretty much the same. But if it's gakkoo, then the hiragana version should be がっこお, which is not OK.

  • 1
    Of course there are always the exceptions, the first of which that comes to mind is 大き (おおき). The others that I know have slipped my mind at the moment. Nov 23, 2018 at 12:43

1 Answer 1


Do you know there are several romanization systems, each of which treats long vowels fairly differently? This Wikipedia article is a good starter.


  • Nihon-shiki/Kunrei-shiki system: gakkô
  • Hepburn system: gakkō (although there are many variants)
  • Passport-shiki system: gakko
  • JSL: gakkoo
  • Wāpuro style: gakkou

If your teacher is using JSL, "gakkoo" is the correct Romanized spelling. Nevertheless, the only correct spelling in hiragana is がっこう.

  • 1
    A long "o" sound is typically written as おお only at the start of a word (e.g. おおきい), and as おう elsewhere, such as in がっこう. Just to make things more confusing, in katakana all long vowels tend to be marked with a dash, e.g. オーストラリア (o-sutoraria for Australia) or カード (ka-do for card).
    – ConMan
    Nov 22, 2018 at 23:40
  • Then there are cases like Inoue which are read Ino-ue and not inoo-e Nov 24, 2018 at 10:11
  • @ConMan I think おお is only for kun'yomi like 大, whereas おう is for on'yomi like 王様(ousama), 桜蘭(ouran), 凹凸(outotsu), 黄金(oukin), 欧米(oubei), and more.
    – Nayuki
    Jun 27, 2020 at 6:01

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