Japanese keyword research is not English keyword research with translated terms. The keyword index behaves differently, search behavior is loanword-skewed, and tooling is less reliable for Japanese than for English. This article covers what to know, what tools to use, and the mistakes to avoid.
For broader listing context, see the Japanese ASO complete guide.
The Three Properties That Make Japanese ASO Different
1. The keyword index tokenizes
Apple's algorithm decomposes Japanese strings into substrings. If you have 「写真」 and 「編集」 in your keyword field, you can rank for the search 「写真編集」 without explicitly listing it. This unlocks compound coverage with shorter character usage.
This also means: don't list overlapping compounds. 「日本」 inside 「日本語」 is already covered.
2. Loanwords often outsearch native equivalents
Japanese has both katakana loanwords and kanji native words for many concepts. Search volume is rarely 50/50; usually one is dominant. Examples:
| Concept | Loanword | Native | Usually winning |
|---|---|---|---|
| Task management | タスク管理 | 課題管理 | タスク管理 (5–10×) |
| Photo editing | 写真編集 | フォトエディタ | 写真編集 |
| Calorie tracker | カロリー計算 | 熱量計算 | カロリー計算 |
| Habit tracker | 習慣化 | 習慣管理 | 習慣化 |
| Calendar | カレンダー | カレンダー | (no native equivalent) |
| Notification | 通知 | ノーティフィケーション | 通知 |
There's no formula. You have to check each concept.
3. Search modifiers are different
US users search "best photo editor app." JP users search 「写真編集」 or 「写真編集 アプリ」 or 「写真加工」 — modifier words like "best," "free," "easy" are searched less often as part of the query. The query patterns are tighter.
The Tools
App Store Connect Search Suggestions
Free, official, and limited. When you enter a keyword in App Store Connect's keyword research tool with a JP storefront, Apple suggests related terms. Useful for adjacency discovery; not great for volume estimation.
AppTweak
Has a Japan locale. Volume estimates are directional, not exact. Best for:
- Comparing relative volumes between candidate keywords.
- Tracking your own ranking on chosen keywords over time.
- Keyword difficulty estimates.
Sensor Tower
Similar coverage. Useful for competitive intelligence on what keywords competitors target.
data.ai (formerly App Annie)
Less keyword-specific but useful for category and competitor analysis at scale.
AppFollow
Decent JP coverage. Good for tracking; weaker for discovery.
Google Trends with Japan filter
Free. Useful for relative volume between two terms. Not specific to App Store search but a reasonable proxy for general interest patterns.
The competitor scrape method (best free option)
Look at the top 20 apps in your category in the JP App Store. Pull their app name, subtitle, and the first 200 characters of their description. The words that appear repeatedly across multiple top apps are the words your target users are searching for.
This method outperforms paid tools for Japanese because it uses what's actually shipping in the market, not a model of search volume.
A Working Keyword Research Method
Step 1: Build a category vocabulary
Open the JP App Store in your category. Make a list of every word that appears in the names and subtitles of the top 20 apps. Translate nothing — copy the Japanese as-is.
For a habit-tracker app, this list might include: 習慣, 続ける, 目標, 管理, 記録, トラッカー, ライフログ, 達成, 毎日, 週間.
Step 2: Check your translated keywords against this list
If your starting keyword list (translated from English) has terms that don't appear in this category vocabulary, those terms are probably wrong. Either you missed a term that should be there, or you're targeting words real users don't search.
Step 3: Volume-rank using a tool
Pull each candidate through AppTweak or Sensor Tower. Note relative volume scores. The highest-volume terms get priority placement (app name, subtitle).
Step 4: Check loanword vs. native splits
For each candidate, check:
- The katakana loanword.
- The kanji native equivalent.
- Hybrid forms (e.g., 写真エディタ).
Pick whichever has higher volume + relevance. Sometimes you include both forms because both have meaningful volume.
Step 5: Map to placement slots
You have:
| Slot | Char limit (JP) | What goes here |
|---|---|---|
| App name | 30 | Brand + 1 high-volume keyword |
| Subtitle | 30 | Highest-intent keyword phrase |
| Keyword field | 100 | Decomposable atoms, comma-separated |
| Description (first 3 lines) | ~120 | Restatement of value prop |
| Description body | 4,000 | Long-tail keywords woven naturally |
| In-app purchase names | varies | IAP names are partially indexed |
The highest-volume, highest-relevance keywords go in the name and subtitle. Decomposition-friendly atoms go in the field.
Common Pitfalls
Pitfall 1: Translating English keyword lists directly
A US keyword list including "easy," "best," "free," "fast" translates to 「簡単」「一番」「無料」「速い」. Some have JP search volume; most don't, because JP users don't search with these modifiers. Strip them before researching JP volume.
Pitfall 2: Listing both 「無料」 and "free"
If your app is free, the App Store automatically marks it as free in the listing chip. You don't need 「無料」 in the keyword field unless your category is specifically searched with the modifier (e.g., 「家計簿 無料」 has real volume; 「カメラ 無料」 doesn't add much).
Pitfall 3: Including particles in the keyword field
「を」「が」「は」「に」「の」「で」 don't help and waste characters. Don't include them.
Pitfall 4: Repeating decomposable substrings
If you have 「日本語学習」 in your subtitle, you don't also need 「日本語」 in the keyword field. The tokenizer covers it.
Pitfall 5: Not separating script forms
「写真」 and 「フォト」 do not share search results. If both have meaningful volume, list both. If one dominates, drop the other.
Pitfall 6: Optimizing for volume without relevance
Targeting a high-volume keyword that doesn't match your app's actual function gets you visits with terrible conversion, lowers your overall conversion-rate signal to Apple, and hurts your ranking long-term. Volume × relevance × intent matter together.
Pitfall 7: Ignoring the subtitle
The subtitle is the highest-leverage 30 characters in the listing after the name. Many teams treat it as decorative ("世界中で愛されています"). Treat it as keyword real estate that reads naturally.
A Worked Example: Japanese Habit Tracker
You ship a habit-tracker app, English name "Habitly." Researching JP keywords:
Step 1: Category vocabulary
Top JP habit-tracker apps include words: 習慣, 習慣化, トラッカー, 続ける, 続けられる, 目標, 達成, ライフログ, 記録, 管理, 毎日, ルーティン, 健康.
Step 2: Check translations
Your initial English-derived list: 「習慣」「追跡」「目標」「毎日」「ヘルシー」.
Compare to category vocab: 「追跡」 doesn't appear in JP habit-tracker apps — they use 「記録」 or 「管理」. 「ヘルシー」 isn't used; 「健康」 is. Update the list.
Step 3: Volume rank
Estimated relative volumes (illustrative):
- 習慣化: high
- 習慣: high
- ルーティン: medium
- 目標達成: medium
- 続ける: medium
- 健康習慣: medium-low
- 記録: high but very broad
- ライフログ: low
Step 4: Loanword split
- 習慣 vs. ハビット: 習慣 wins by a wide margin.
- 目標 vs. ゴール: 目標 wins.
- ルーティン vs. 日課: ルーティン wins for app context.
Step 5: Placement
- App name: "Habitly" — 習慣を続ける (28 chars total)
- Subtitle: 毎日のルーティンで、目標達成 (15 chars)
- Keyword field: 習慣化,目標,記録,健康,ライフログ,続ける,達成,管理,ハビット,ルーティン,週間 (uses ~75/100 chars)
The app name keeps the brand and adds a category descriptor. The subtitle leads with the highest-intent phrase. The keyword field uses decomposable atoms across the full keyword set.
Validation: Did the Research Work?
After launching the optimized listing:
- Indexed terms. Use a tool to verify which keywords your app ranks for. Many should match your target list.
- Impressions. Total impressions should grow (Apple is showing you in search).
- Conversion rate. Stable or growing CR confirms the keywords match your actual app.
- Rank movement. You should see your app climbing on target keywords over 2–4 weeks.
If impressions grow but CR drops, the keywords are too broad or off-topic. If both rise, the research worked. Iterate every quarter.
Where to Go Next
- Writing App Store Descriptions That Convert in Japan
- Localizing Your App Name and Subtitle for the Japanese App Store
- Designing App Store Screenshots for the Japanese Market
- Custom Product Pages for Japan
We do Japanese keyword research and listing optimization as a fixed-scope engagement. Contact us for a JP keyword strategy specific to your category.