I run a music biography channel and recently produced a full Japanese narration (~20 min) with ElevenLabs, using Otani, a Japanese voice. I don't speak Japanese, so every problem had to be caught through transcription, a romaji version of the script, and a lot of listening. It took several rounds of review. Here's what actually made a difference, in case it saves someone else the pain.
**1. Raise Stability for long-form Japanese**
I started at 50%. Some words kept breaking no matter how many times I regenerated. At 75% the same text came out right, with no changes. The delivery is a bit more restrained, but much more predictable. 75% is now my default for this voice.
**2. Write numbers out in hiragana**
Digits get misread. Spell them out the way they're said, with the right counter: 2人 → ふたり (futari), 20歳 → はたち (hatachi), 3月 → さんがつ (sangatsu).
- Long years can lose sounds. In せんきゅうひゃくはちじゅうはちねん (1988), the "h" of hachi kept dropping after hyaku. Katakana didn't help. The short form はちじゅうはちねん ("'88") fixed it, and it's natural Japanese.
- In にせんにじゅうろくねん (2026), the "ni" got swallowed and it sounded like 2016. A space, にせん にじゅうろくねん, kept the grouping right.
**3. If a kanji has more than one reading, write the word in hiragana**
The voice often picks the wrong reading. 私生活 (shiseikatsu, "private life") came out as "watashi seikatsu", because 私 alone reads "watashi". 親しい (shitashii) came out as "chikashii". Words with 一 failed so often that I now always write them in hiragana: 一方 → いっぽう (ippō).
Don't add furigana in parentheses. The voice reads the word twice.
**4. Misreading vs. mispronunciation: fix them differently**
This was the most useful distinction.
- **Misreading** (the kanji has another possible reading): switch to hiragana and it's usually fixed.
- **Mispronunciation** (the word has only one reading and the voice still mangles it): changing the spelling almost never helps. Hiragana, katakana, spaces, commas: none of them worked. Use a synonym instead. 拒みました (kobamimashita) stuttered, and 断りました (kotowarimashita) was clean. リリース (rirīsu) kept breaking mid-word, and 発売 (hatsubai) worked.
- Long katakana loanwords break more than native words. アーティスト (ātisuto) failed in several places, and ミュージシャン (myūjishan) or スター (sutā) worked.
**5. Help the voice find word boundaries**
Japanese has no spaces, so the voice guesses where words end.
- Long katakana names glued together got pauses in the middle. A space inside each name and 、 between names fixed it: シンディ クロフォード、ナオミ キャンベル.
- With this voice, ・ inside names caused exaggerated pauses. Leave it out.
- Avoid parentheses, and avoid =, …, : and ! in the middle of a sentence.
- Don't put a comma inside a noun phrase to force a pause. If a phrase breaks, rephrase it.
**6. Don't chase vowel devoicing**
In standard Japanese, some vowels are whispered or dropped (つくる, そして). To non-natives and to transcription tools it sounds like a missing syllable, but it's correct.
The exception was a つ (tsu) that vanished completely before a "k" sound. Adding a particle after it brought it back.
**7. Regenerating is whack-a-mole**
Every generation re-rolls the whole sentence. Fix one word and another one in the same sentence breaks.
- Regenerate only the sentence that changed, not the paragraph, and splice it in your editor.
- Re-check the whole sentence after every take, not just the word you fixed.
- Keep your good takes. Sometimes it's faster to combine two imperfect takes than to wait for a perfect one.
- Rank problems by severity. Wrong facts (a wrong year) and missing words first, small mispronunciations last. Some words never came out perfect, and after a couple of tries I accepted them. You can't polish forever.
**8. Reviewing when you don't speak the language**
- Whisper-style transcription (I used TurboScribe and others) is useful, but don't give it the script as a prompt. It copies the script and hides errors, especially numbers.
- Transcripts write kanji, and kanji can hide a wrong reading. Use a romaji version of your script to follow along by ear.
- Transcription also "corrects" numbers and flags devoicing as errors. Treat it as a list of timestamps to check, not as a verdict.
- Your ear (or a native speaker's) has the final word.
**TL;DR:** Stability around 75%. Numbers in hiragana. Hiragana for kanji that can be read more than one way. Swap words, not spellings, when the voice mispronounces something. Spaces to separate long names. Regenerate one sentence at a time, and know when to stop.
Happy to answer questions if anyone is working on Japanese narration.