Making AI-Sounding Japanese Natural — the natural-japanese Skill
機械翻訳 / Machine-translated
cccskills
2026年10月11日・22分で読める
機械翻訳 / Machine-translated
Original article: Making AI-Sounding Japanese Natural — the natural-japanese Skill (cccskills)
Skill page: natural-japanese
Key takeaways from this article
With natural-japanese installed, you can take AI-written meeting minutes, reports, and blog posts and turn them into readable Japanese without altering any facts.
The most important rule is never to add facts or figures that don't appear in the original document.
This article walks through how to detect and fix AI-like qualities, how to choose between Quick and Full modes, how to install the skill, and how to request a diagnosis-only run.
Turn this transcript into meeting minutes without mixing up what was decided
The minutes you get back are built solely from the statements and decisions present in the transcript.
The agent reads the guidelines for meeting minutes, verifies the required elements and common AI pitfalls, and only then begins writing.
After finishing, it runs the bundled check script to confirm that no prohibited words or translation-style phrasing remain.
The difference shows up in how undecided matters are written.
A remark like "we agreed to revisit how this ultimately gets decided at the next meeting" will not be rendered as "Agreed on the policy direction. Tanaka to produce a concrete proposal by July 18."
Instead it becomes "The decision was carried over to the next meeting," preserving the original level of certainty.
The most important rule of this skill is never to add facts, figures, names, dates, or conditions that don't exist in the source material.
When the source material is insufficient, the agent does not fill gaps with guesswork — it tells the user what is missing.
The response also lists, for each item the script flagged, whether it was "fixed" or "kept," along with the reason.
natural-japanese is a skill for writing and revising Japanese documents used at work so they read naturally and clearly.
Target document types include meeting minutes, research reports, internal guides, technical articles, PR copy, research memos, project proposals, emails, and slide outlines.
It can also be used for writing notes, blog posts, and essays.
When writing something new, the skill establishes the main message in a single sentence before the body text begins.
Headings are not vague labels like "Background" or "Summary" — they state the conclusion of that section.
By following principles such as leading with conclusions and separating facts from opinions, the basics of business writing naturally fall into place.
Detecting suspicious passages is handled mechanically by the bundled script.
It flags prohibited words, translation-style phrasing, overuse of "〜ではなく" (rather than), monotonous sentence lengths, repeated vocabulary, and direct translations of English syntax.
Because AI tends not to notice its own writing habits, detection is deliberately left to the machine.
Script flags are treated as suspicions, not verdicts.
The agent weighs each flag against context to decide whether to fix or keep it; if keeping, it records a reason such as "part of a proper noun" or "technical term."
Specifying a genre — essay, technical, or business — adjusts the judgment criteria accordingly and reduces false positives.
Phrasing the script cannot easily catch is reviewed paragraph by paragraph. This includes:
Rhetorical intensifiers are simply deleted — not replaced with alternative wording.
"An overwhelming number of users" becomes "many users," not "a very large number of users."
Word order, comma placement, one-idea-per-sentence structure, and the distance between subject and predicate are all checked.
The target sentence length is 50–60 characters; long modifying phrases are placed before what they modify.
Runs of seven or more consecutive kanji are broken up with hiragana, and "〜することができる" is shortened to "〜できる."
The same process runs in two modes with different levels of thoroughness:
| Quick (default) | Full | |
|---|---|---|
| Best for | Everyday documents | Documents where errors carry significant weight (external/executive-facing), or documents exceeding 10,000 characters |
| Scope | Runs the check once; verifies structure via headings and opening sentences of paragraphs | Also outputs a structure summary and terminology list; checks all structure and readability |
| Estimated time | ~30 seconds for meeting notes; ~3 minutes for 10,000-character documents | ~7 minutes for short documents; 15–20 minutes for 10,000-character documents |
Adding "thoroughly" or "take your time" to a request triggers Full mode.
When in doubt, the skill finishes in Quick mode and returns the result with a note that a Full review is also available.
You can ask for a diagnosis without any rewriting.
The skill will assess and score AI-like qualities and will not rewrite anything until asked.
For style learning, hand over 3–5 past pieces of writing and the skill will extract a style profile capturing your perspective, vocabulary, and rhythmic tendencies.
This profile is then applied to future writing.
Run the following command in your terminal:
npx skills add https://github.com/coji/natural-japanese --skill natural-japanese
To have Claude Code install it for you, send the following message exactly as written.
It asks Claude to review the contents before placing the files:
次の Agent Skill をインストールしてください。
https://github.com/coji/natural-japanese/tree/main/skills/natural-japanese
まず SKILL.md と付属ファイルの中身を確認し、不審な処理（外部への送信、認証情報の読み取りなど）がないことを確かめてから、~/.claude/skills/natural-japanese/ に配置してください。
To use the skill across all projects, place it in ~/.claude/skills/; to use it in a specific project only, place it in that project's .claude/skills/ folder.
The distribution source is coji/natural-japanese.
You can invoke the skill in plain language.
"Write about ○○" is treated as a new writing request; "Does this text sound AI-written?" is treated as a diagnosis request.
The command-line syntax is as follows:
/natural-japanese [quick|full] <target>
/natural-japanese write [quick|full] <topic or material>
/natural-japanese score [quick|full|exp] <file>
The first line writes or revises (default), the second creates something new, and the third diagnoses without rewriting.
Make this report more readable without changing any facts or conditions
You get back a report with only the phrasing revised, plus a log of how each flag was handled.
Even when shortening headings or opening summaries, the conditions in the body text are not dropped.
"Users on annual contracts who exceed 100 uses per month are eligible for a discount" is never summarized as "heavy users get a discount."
As a final step, the skill lists any figures and proper nouns that appear only in the revised document to confirm that no new facts were added.
If a number in the source is inconsistent, it is not corrected — the user is notified instead.
Diagnose how AI-like this text is. No rewriting needed.
This request triggers diagnosis mode and the document is left untouched.
You receive a score and diagnostic results, sometimes accompanied by rewrite suggestions.
Actual revisions are only made if you follow up with another request.
I'll give you five past blog posts — learn my writing style from them
What you get is a style profile that summarizes your tendencies in perspective, vocabulary, and rhythm as patterns.
Telling the skill "I wouldn't use that phrasing" causes that combination to be recorded as an expression to avoid.
Individual words are not blanket-banned.
Mechanical detection runs the bundled Python script via uv.
In environments where uv is unavailable (such as Claude.ai), the same criteria are checked manually following the manual inspection procedure.
The experimental detector for topic flatness is optional and requires downloading a model of approximately 1 GB on first use.
It is only used in Full mode when the environment permits.
In environments that allow effort selection, high is recommended so that Full-mode steps are less likely to be skipped.
Temporary files created during processing are placed in a temporary directory and deleted upon completion.
What remains in the project is only the finished document and, if requested, the style profile.
The license is MIT.
Please review SKILL.md and the bundled scripts before installing.
writing-shape is a skill for organizing source material such as notes or transcripts into an article structured in the order most understandable to readers.
It pairs well with natural-japanese when used in sequence: lock down the structure first with writing-shape, then hand off the phrasing to natural-japanese.
brand-voice is a skill for extracting and organizing the tone and stylistic characteristics of a voice from actual posts, articles, and emails.
It is an option for those who want to apply a consistent style across social media posts and sales emails.
Yes. The revision process does not change based on whether the author is human or AI.
Distinguishing between the two from text alone is difficult, and documents written by newer models tend to generate fewer script flags.
There is a mechanism that lists figures, proper nouns, and alphabetic terms that appear only in the revised document.
However, it cannot catch details added using ordinary nouns, shifts in the level of certainty, or swapped speakers.
As a final step, compare the revised document against the original with your own eyes.
In essays, the skill recognizes writing styles that leave things open-ended or place conclusions at the end as intentional choices by the author.
If you indicate that a particular tone is intentional, rhetorical language will not be removed.
Colloquial quotations and emoji are also left in as long as they do not impede comprehension.
A manual inspection procedure is provided for environments where uv is unavailable.
Instead of script-based detection, the same criteria are checked by eye.
natural-japanese is a skill focused specifically on the naturalness and readability of Japanese documents used at work.
Suspicious passages are caught mechanically, decisions on whether to fix them are made in context, and nothing not present in the source is ever added.
Whether you need to draft meeting minutes, revise a report, get a diagnosis without rewriting, or learn a writing style, you can tailor your request to fit the use case.
Installation details and more information are available on the cccskills page.
This article is a repost of "Making AI-Sounding Japanese Natural — the natural-japanese Skill" from cccskills.
Full details and installation instructions for the skill can be found on the cccskills natural-japanese page.