Do Japanese characters in URLs really block indexing beyond 100 pages?

Where does this urban legend about 100 URLs come from?

This belief has circulated in Japanese SEO communities for years: the idea that beyond 100 pages with Japanese URLs, Google would stop indexing content. The logic behind it? Non-ASCII URLs require percent encoding (e.g., %E3%81%93), which would considerably lengthen the strings and consume too much crawl resources.

However, Google firmly denies this. No arbitrary limit is coded in the algorithm on this criterion. The engine treats encoded URLs like any other URL — percent encoding is transparent to Googlebot. If a site reaches 101, 500, or 5000 pages with Japanese slugs, there is nothing structurally blocking the indexing for that reason.

Why do some sites still experience issues?

Because correlation does not imply causation. A site that exceeds 100 pages is often one that is growing rapidly — and accumulating other problems: duplicate content, thin content, poorly managed pagination, insufficient crawl budget facing a heavy structure, chain redirects, etc.

The threshold of "100 pages" is nothing magical. It’s simply the point where certain structural flaws become critical. If indexing drops at this stage, it's not the Japanese URL that is the issue — it’s the overall technical health of the site reaching a breaking point. The Japanese characters in the slugs then become the convenient scapegoat.

What does Search Console really say in these cases?

Google’s recommendation is clear: diagnose via Search Console, not via folk hypotheses. The tool precisely reports the discovered, crawled, indexed URLs, and those rejected — with the actual reasons: unintentional noindex, canonicalization to another page, soft 404, content deemed too weak, exceeded crawl quota, etc.

None of these reports ever mention "Japanese URL" as the cause of a block. If indexing collapses, it is always for an identifiable technical reason — and this will be documented in the coverage, crawl, or quality reports. Ignoring these diagnostics to blame URL encoding is to miss the real problem.

• No technical limit on indexing related to Japanese characters in custom URLs
• Indexing issues on Japanese sites with over 100 pages stem from other structural causes (crawl budget, content quality, duplication)
• Search Console is the only reliable tool to identify the true causes of non-indexation
• Percent encoding of non-ASCII URLs is transparent to Googlebot — no processing penalties

Does this claim align with field observations?

Overall, yes. Documented cases of Japanese sites losing their indexing after 100 pages never show a direct and exclusive correlation with the use of Japanese characters in the slugs. When auditing these sites, classic problems are invariably found: pagination without rel=next/prev (or without proper canonicalization), explosion of URL parameter counts, poor auto-generated content, chaotic internal linking.

That said, the encoding of Japanese URLs can indirectly worsen certain issues. For example, a URL with 50 Japanese characters encoded can reach 150+ bytes — which consumes more crawl budget per request. On a site with thousands of pages and a limited crawl budget, this can slow the discovery of new content. But this is not a "block" — it’s a crawl friction, technically different.

What nuances should be added to this statement?

Google is telling the truth, but it’s an incomplete truth. No arbitrary limit at 100 pages, certainly. But there are real, unannounced limits related to crawl budget and perceived content quality. A site with 500 pages of low added value — whether it uses Japanese URLs or alphanumeric ones — will be partially indexed, end of story.

Moreover, some poorly configured CMS or frameworks generate faulty encoded URLs when using non-ASCII characters. Double encoding, incorrect escaping, duplicate URLs between encoded and non-encoded versions — these bugs exist and create duplicate content that Googlebot consolidates via canonicalization. The problem is not the "Japanese URL," but the poor technical management of it. [To be verified]: Google has never provided quantified data on the actual impact of percent encoding on crawl budget — its statements remain qualitative.

In what cases might this rule not apply?

If a site abuses extremely long Japanese slugs (say 200+ characters encoded into 600+ bytes), and multiplies this pattern across thousands of low-value pages, it’s possible that Googlebot prioritizes other sections of the site and leaves these URLs perpetually at the tail of the crawl. This is not a "limit of 100 pages" — it is an algorithmic deprioritization based on crawl ROI.

Another case: sites with URL duplication issues (encoded vs. non-encoded versions accessible simultaneously, absence of clear canonicalization). Here, Google may index one version and ignore the other — which gives the impression of a "limit" while it’s a consolidation of duplicate content. The culprit is not the Japanese URL, but the shaky technical architecture.

Should you avoid Japanese URLs to ensure indexing?

No. Using Japanese characters in your slugs is not an indexing risk in itself. If your site is technically healthy — original content, coherent internal linking, respected crawl budget, no massive duplication — you can index thousands of pages with Japanese URLs without artificial limitations.

However, favor short and descriptive slugs. A URL of 10-15 Japanese characters (30-45 encoded bytes) is reasonable. Beyond 50 characters, you waste crawl budget unnecessarily and complicate social sharing (truncated URLs become unreadable). This is not blocking, but it’s suboptimal.

How to diagnose a real indexing problem on a Japanese site?

First step: Search Console, Index Coverage tab. Look at the excluded URLs and their reasons. If you see "Crawled, currently not indexed" in large numbers, it means Googlebot is visiting your pages but judging their content insufficient or redundant — nothing to do with URL encoding.

Second step: check accessibility and canonicalization. Test your encoded URLs in a browser, then in the URL Inspection tool of Search Console. Ensure that the canonical version corresponds well to the URL you wish to index, and that there isn’t a duplicate version accessible by an alternative URL (with or without trailing slash, with or without www, encoded differently, etc.).

What technical errors should you absolutely avoid?

Double encoding is the classic trap. If your CMS encodes the URL once, then a plugin or CDN re-encodes it, you end up with a broken URL (e.g., %25E3 instead of %E3). Googlebot cannot crawl this page — or crawls it but considers it a soft 404 error.

Another common mistake: poorly configured 301 redirects during a migration. If you transition from alphanumeric URLs to Japanese URLs (or vice versa), and your server does not properly handle encoding in the Location header, the redirects fail or loop. The result: a sharp loss of indexing that you wrongfully attribute to "Japanese URLs" while it’s a server configuration error.

• Audit your encoded URLs in Search Console to detect any crawl or indexing issues — do not rely on assumptions
• Limit the length of your Japanese slugs to 10-20 characters to optimize crawl budget and readability
• Test canonicalization: make sure only one version of each page is accessible and marked as canonical
• Check that your 301 redirects properly handle percent encoding (test with curl or an HTTP debugging tool)
• Monitor the reports "Crawled, currently not indexed": they reveal content quality issues, not URL encoding issues
• If you use a CDN, confirm it preserves URL encoding in headers (Location, Link, etc.) without double encoding