I realize that it's usually better to just learn / use hiragana but I have been asked to look into coding up a solution to convert from Hiragana/Katakana to the modified Hepburn Romaji.

One point I would like some advice on is the conversion of:


I see some converters changing this to:


and others to:


Is there one or the other that I should aim for with the Modified Hepburn?

  • 2
    What is the purpose of this romanized text? Will this romanized text be used later to reproduce the kana rendering? Is this intended for humans to read? Running everything together produces a largely unreadable result. If you're interested in a human-readable output, have a look at Wiktionary's coding module: en.wiktionary.org/wiki/Module:ja Mar 20, 2017 at 16:17
  • My opinion is that wo is better, just for the sake of unambiguity/specificity.
    – Kurausukun
    Mar 20, 2017 at 17:21

2 Answers 2


As Eiríkr Útlendi mentioned in a comment, the correct romanization for を in modified Hepburn is o.

For traditional Hepburn, the correct romanization is wo.

To blatantly steal his wikipedia link as well, here's the reference. For a programming project, you should be able to use the table at the end of that page for a dict/hash translation. (with some special handling for ん)


is correct for modified hepburn, but since you lack the word seperation functions of kanji/kana alternation with romaji, people usually seperate words with spaces when using romaji.

  • Just thought I'd provide a link to a simple Javascript implementation of the translation table referenced in that Wikipedia article: gist.github.com/Venryx/ecbea1a0c7a8a6cb21d80886488045f1 It's not perfect -- there are still some edge-cases it doesn't handle -- but it works for 95+% of words, which is good enough for my personal use case. If someone knows a light-weight existing library that accomplishes this conversion function (but with all edge-cases correctly handled), please let me/us know.
    – Venryx
    Jun 4, 2019 at 4:42

The correct romaji way is wo.

"O" is how you pronounce it and it's unnecessary since the first thing we learn in Japanese is that を has one use and it's pronounced "o" but written "wo".

We can also distinguish better what each word is in "kaimonowoshimasu".

  • 3
    Citation for "correct way"? There are multiple ways to transliterate Japanese into English. They are "correct" for different purposes
    – virmaior
    Mar 20, 2017 at 19:30
  • 3
    The asker also specifically mentioned Modified Hepburn, which renders the particle を as "o". Mar 20, 2017 at 19:42

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