Japanese App Store keywords: katakana vs kanji vs romaji

Of all the markets indie devs typically half-ass in their localization, Japan is the worst-handled one. Not because Japanese is hard — though it is — but because Japanese ASO has a structural quirk that no other market really has: the same word can be searched in three different scripts, with wildly different volumes for each, and picking the wrong script in your title silently halves your indexation.

Here's how that actually works, and what to do about it.

The three-script problem

Japanese is written in three scripts that are routinely mixed in everyday text:

• Hiragana (ひらがな) — the cursive phonetic script, used for grammar and native words
• Katakana (カタカナ) — the angular phonetic script, used overwhelmingly for foreign loanwords (英語の言葉, "English words")
• Kanji (漢字) — Chinese-origin characters, used for native concepts, names, and the bones of most nouns and verbs

Romaji (Latin alphabet, like "Tokyo") exists too but is rarely how Japanese users search the App Store.

For ASO, the quirk is this: many concepts have a katakana version (a transliterated English loanword) and a kanji version (a native Japanese word). Both are valid. Both are searched. The volume split between them depends on the concept and is often counterintuitive.

A worked example: "yoga"

The English word "yoga" exists in Japanese in three forms:

• ヨガ (yoga, in katakana — the loanword form)
• 瑜伽 (yoga, in kanji — the original Sanskrit-derived form)
• yoga (in romaji)

Apple's autocomplete in Japan for the seed "yoga":

• ヨガ (huge volume)
• ヨガアプリ (yoga app)
• ヨガ ポーズ (yoga poses)
• ヨガ 初心者 (yoga beginner)

For the seed "瑜伽":

• 瑜伽 (low volume)
• A handful of niche suggestions

For "yoga" in romaji:

• Almost nothing — Japanese users rarely search in romaji

The katakana form (ヨガ) wins decisively. A yoga app whose Japanese title is "瑜伽スタジオ" (yoga studio in kanji) will rank dramatically worse than "ヨガスタジオ" (yoga studio in katakana), even though both are valid Japanese.

A counter-example: "meditation"

"Meditation" in Japanese:

• 瞑想 (meisō, in kanji — the native Buddhist-tradition word)
• メディテーション (meditation, in katakana — the loanword)

Apple's autocomplete in Japan for "瞑想":

• 瞑想
• 瞑想 アプリ (meditation app)
• 瞑想 音楽 (meditation music)
• 瞑想 ガイド (meditation guide)

For "メディテーション":

• A handful of suggestions, much lower volume

In this case, the kanji form wins. Why? Meditation has a deep cultural history in Japan tied to Buddhism, and the kanji 瞑想 carries that resonance. The katakana form feels imported and slightly clinical. Japanese users searching for a meditation app overwhelmingly type 瞑想.

The pattern (sort of)

There's no clean rule, but the rough heuristic:

• Modern Western imports (yoga, smoothie, podcast, marketing): katakana wins
• Native cultural concepts (meditation, calligraphy, tea ceremony, traditional crafts): kanji wins
• Tech-adjacent concepts (app, website, AI, photo): katakana usually wins
• Family, home, body, food (basic concepts): kanji usually wins

The only way to know for sure is to check Apple and Google autocomplete in Japan. The two stores often have slightly different splits — Google Play tends to surface katakana more aggressively, Apple tends to surface kanji more for traditional concepts.

What this means for your title

Your iOS Japanese title gets 30 characters. In Japanese, characters are full-width — each kanji or katakana character takes the same visual space as a Latin letter, but Apple counts it as one character of your 30-char budget.

This means a 30-char Japanese title is much more information-dense than a 30-char English title. You can fit a brand name, a primary keyword, AND a benefit modifier comfortably:

• "Posterly — 星座マップ ポスター" (Posterly — Star Map Poster) — 22 chars

The challenge is: which script for which token?

For "Posterly" (the brand): leave in romaji. Brands generally don't translate.

For "star map" (the concept): katakana wins (スターマップ) for tech-modern framing, kanji (星座) for the traditional astronomy framing. Run autocomplete in both forms to confirm which has higher volume in your category.

For "poster" (the product): katakana (ポスター) wins overwhelmingly. The Japanese word would be 掛け軸 but that means traditional hanging scroll, not modern art print.

Putting it together: "Posterly — 星座マップ ポスター" mixes scripts deliberately — kanji for the traditional astronomy concept, katakana for the modern product type. This is normal, even idiomatic, and ranks better than picking either script exclusively.

The keywords field in Japan

Apple's keywords field in Japan accepts all three scripts. The strategy:

• Don't repeat tokens already in the title
• Cover the other script form of your most important concept (if your title uses katakana ヨガ, put 瑜伽 in keywords; if your title uses kanji 瞑想, put メディテーション in keywords)
• Add 5–8 niche modifiers in whichever script the autocomplete confirms is dominant for that modifier

A poster app's es-JP keywords field might look like:

カスタム,プレゼント,記念日,結婚祝い,寝室,星空,贈り物,星座

(Custom, present, anniversary, wedding gift, bedroom, starry sky, gift, constellation — mix of katakana for product/use-case modifiers and kanji for cultural/relational concepts.)

The Google Play long description in Japanese

Google Play's long description in Japanese has the same density advantage as the title — you can pack a lot of information into 4000 characters when each character is a full word-fragment.

The honest mistake to avoid: writing the long description in English-flavored Japanese (i.e., heavy on katakana loanwords). This reads as marketing-speak and Japanese users skim past it. Native-feeling Japanese long descriptions:

• Open with a concrete benefit, not a brand statement
• Use kanji for the cultural/emotional anchors of the use case
• Use katakana for the product type and tech-adjacent terms
• Vary sentence length — Japanese marketing copy that uses consistent short sentences feels translated; long, varied sentences with appropriate particles feels native

The store algorithm doesn't care about reading quality, but Japanese users do, and conversion rate compounds with rank.

The romaji edge case

There is one place romaji genuinely wins in Japanese ASO: brand names.

If your app is called "Posterly" and your Japanese title forces it into katakana ("ポスタリー"), you've damaged your brand recognisability and gained essentially zero search volume — Japanese users searching for your specific app will type "Posterly" in romaji or just type a category term and look for the icon.

The right move: keep your brand in romaji even in the Japanese title. Mix it freely with kanji and katakana. "Posterly — 星座マップ" is correct. "ポスタリー — 星座マップ" is worse.

Korea has a related but different problem

Korean ASO has its own quirk: hangul-only titles convert better than mixed English/Korean titles, even though Korean users freely mix the two scripts in everyday writing. We'll cover this in a separate post — it's worth its own treatment.

How ASO Pilot handles Japan

When you select Japan as a target market in ASO Pilot, the engine knows to:

• Generate the title with appropriate script-mixing (brand in romaji, modern product type in katakana, cultural anchors in kanji)
• Validate the chosen scripts against Apple's autocomplete in Japan before scoring keyword candidates
• Avoid the common indie mistake of forcing the brand into katakana or trying to render everything in kanji

The Audit tab also flags this on existing apps — if you import a Japanese listing whose title is all in romaji or all in one script, the audit will surface "No localised metadata for CJK markets" with a concrete suggested rewrite using the correct script mix.

If you're shipping into Japan and unsure whether you've made the right script choices, run a free analysis with Japan as a target market. The engine will tell you, with autocomplete-verified evidence, which script forms have the highest demand for your category.

Bottom line

Japanese is not a "set the locale to ja-JP and run Google Translate" market. The three-script system creates a distinct ASO problem that translation pipelines structurally cannot solve. Picking the right script per term — and especially for your title's main keyword — is the single highest-leverage move you can make in Japanese ASO.

For the tool that does this for you: ASO Pilot, free tier includes Japan in your 3-market quota.