Perhaps this question is completely unimportant, but I do not know if it is.

There is a very influential mathematical paper by Alexander Grothendieck often called his Tôhoku paper, because of the journal that published it in 1957.

When I look online now, the only people who use the accent ô are mathematicians referring to this paper. Everybody who is just writing about the place 東北地方 uses the accent ō and writes Tōhoku.

Wikipedia suggests the spelling Tôhoku is the Kunrei-shiki or Nihon-shiki version, while Tōhoku is the Hepburn or Revised Hepburn version. Is that true?

Do Japanese speakers today make any distinction between ô and ō in romanization? Or is it just a trivial choice between notations?

  • There is no official standard of romanization, it doesn't have much to do with Japanese language. There is no distinction in kana.
    – macraf
    Mar 1, 2017 at 6:10
  • 1
    @macraf That is actually not true. ISO 3602 was declared by the Japanese government as an official romaji standard. (decreed in Japanese Cabinet Order No 1 as of Dec 29, 1954). Unfortunately the order gave an exception for following "established precedent", and Hepburn is probably more common than not, even in official writing.
    – jkerian
    Mar 1, 2017 at 16:35

2 Answers 2


As @naruto notes, the difference between Tôhoku and Tōhoku is only a difference of romanization systems. (Both are correct transliterations of 東北 in their respective systems.) A number of romanization systems are used in Japan, so Japanese speakers will probably not give it a second thought.

Presumably the reason that the paper is referred to as the Tôhoku paper is that at the time of publication (1957) the official name of the journal was Tôhoku Mathematical Journal. Only in 1999 was the name of the journal changed to Tohoku Mathematical Journal (unfortunately obscuring the long vowel by not using any standard romanization):

First, we redesigned the cover from Volume 51 in 1999, and adopted "Tohoku Mathematical Journal" instead of "Tôhoku Mathematical Journal" as the offical name.

The journal appears to have a Japanese name 東北数學雑誌 Tōhoku Sūgaku Zasshi (in Hepburn) on the cover.


But if the official name was Tôhoku Mathematical Journal (now Tohoku Mathematical Journal), then this is the name one should probably use to refer to it.


Do Japanese speakers today make any distinction between ô and ō in romanization?


Or is it just a trivial choice between notations?


Long answer: As explained on Wikipedia, elementary school children firstly learn romaji using the Kunrei system, which is simpler than the Hepburn system. And the Kunrei system taught at elementary school usually uses ô for some reason.

After they graduate elementary school and are exposed to more and more English words, they gradually realize that the Hepburn/passport system look more natural to the eyes of English speakers, and that ô is rarely used to describe long vowels in actual business scenes. Anyway, ô is just another notation for long vowels, and there is no important difference. I don't know why you see only Tôhoku that often. Perhaps someone happened to use Tôhoku, and everyone followed without thinking much about it.

  • Maybe the reason mathematicians use it is that at first many people who wrote about it were French, and French already has the accent ô, while it does not have ō. Mar 1, 2017 at 7:20
  • I don't know why you see only Tôhoku that often. I think because at the time of publication (and for the next 40+ years) the name of the journal was Tôhoku Mathematical Journal, with ô.
    – Earthliŋ
    Mar 1, 2017 at 11:04

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