[BUG] Feedback on Japanese Comma Usage in Claude (Opus 4.7) — Excessive Comma Insertion Disrupts Narration

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Hello Anthropic team,

I'd like to share feedback on a recurring issue I've observed with Japanese text generation in Claude Opus 4.7, which significantly impacts my production workflow (YouTube narration scripts).

The Issue: Excessive Comma Insertion

Claude tends to insert Japanese commas (読点「、」) at nearly every phrase boundary (文節境界), producing overly fragmented sentences.

Example (problematic output):

俺は、手を、合わせながら、目を、閉じていた。

Natural Japanese would be:

俺は手を合わせながら、目を閉じていた。

Why This Is a Problem

1. Unnatural rhythm: Native Japanese readers place commas based on breathing cadence and semantic grouping, not mechanical phrase-boundary detection.
2. Breaks narration flow: In voice-over production, narrators pause at every comma. Excessive commas make the audio choppy and robotic.
3. Emotional scenes suffer most: At climactic moments, over-commafication fragments the emotional impact — viewers disengage from the story.

Suspected Root Cause

Claude appears to treat comma placement as a "safe-by-default" operation, inserting them at every detectable 文節 boundary rather than applying semantic/rhythmic judgment. This behavior is consistent across sessions and prompts, suggesting it's baked into the model's Japanese generation pattern.

Impact on My Workflow

I produce Japanese narration scripts (~45,000 characters each) using Claude. I currently have to manually correct hundreds of over-inserted commas per script, or add aggressive prompt-level rules to suppress the behavior — neither of which fully solves the issue.

Suggested Improvement

Please consider training/tuning Japanese output to use commas based on:

• Semantic grouping (clause-level pauses, not phrase-level)
• Natural reading rhythm (avoid commas between tightly-bound elements like subject + immediate verb)
• Frequency reduction overall — native Japanese prose uses far fewer commas than Claude currently produces

Thank you for your continued work on Claude. It's been an invaluable tool for my production pipeline, and I hope this feedback helps improve Japanese output quality.

Best regards,

What Should Happen?

■ What should have happened?

Claude should place commas based on semantic grouping and natural reading rhythm, not mechanical phrase-boundary detection.

Expected output for the same sentence:
俺は手を合わせながら、目を閉じていた。

Specifically:

Place commas at clause-level pauses, not at every 文節
Avoid commas between tightly-bound elements (subject + immediate verb, verb + object)
Use roughly 1/3 to 1/2 the number of commas Claude currently inserts
Apply rhythmic judgment (how it sounds when read aloud), especially for narrative prose

Error Messages/Logs

Steps to Reproduce

Ask Claude Opus 4.7 to write any Japanese narrative prose (e.g., a short story, a narration script, a scene description) of 1,000+ characters.
Observe comma placement in the output.
Result: commas appear at nearly every 文節 boundary, creating fragmented sentences.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

NEW

Claude Code Version

Claud4.7

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_