Japan has the highest app and SaaS ARPU in the world, and it's the market foreign software teams most consistently leave on the table — not because the product is wrong for Japan, but because of four small, boring gaps a Japanese buyer checks in the first ninety seconds. I'm a Tokyo-native builder. I scored 16 foreign dev tools against those signals. The scores ran 11–28 out of 100. The striking part wasn't any single product — it was how identical the gaps were.
Cal.com ships thousands of Japanese translation strings in the repo. The live site routes none of them — no hreflang ja, no /ja path a Japanese visitor or google.co.jp ever lands on. The translation exists and is invisible at the same time. Chatwoot's app ships a Japanese locale (ja.yml); the funnel that decides whether a Japanese team ever reaches that app is English-only. Rallly's app speaks Japanese; the site that sells it doesn't.
A Japanese team evaluating you never sees the part that already works in their language. You paid for the localization and then hid it behind an English funnel.
特商法 (the Specified Commercial Transactions Act disclosure) is a baseline trust-and-commerce signal in Japan. For consumer apps it's a nice-to-have; for anything a Japanese company runs through procurement — most B2B SaaS — its absence is a quiet disqualifier. A reviewer sees no 特商法 page and stops, regardless of how good the product is. Of the 16 tools I checked, zero had one.
A Japanese enterprise paying a recurring USD invoice inherits currency conversion, exchange-rate verification, and a foreign-currency approval step — every renewal. JPY pricing removes all of it and removes the "foreign vendor" feeling from the contract itself. Almost every tool I scored prices in USD (a few in EUR), with no JPY path.
With no Japanese pages, there's nothing indexed for the high-intent queries a Japanese buyer types — 「(category) 比較」, 「(category) おすすめ」, 「LaTeX 代替」, 「電子署名 オープンソース」. The buyer searches in Japanese, finds a domestic competitor that did localize, and shortlists them before you're evaluated on the merits.
Look at the four together and the failure mode is clear: the demand is often already proven, and the supply is missing by inches.
In every one of these, Japanese users showed up, raised their hand, and hit a wall. They don't email you about it. They churn silently to a competitor who speaks their language.
ja page (hreflang + a real /ja route), or does your locale work sit unused in the repo?Want it scored for you? I publish free gap maps — one per product, verified against the live site, no signup: jp-ready.glovrex.com. There's also a 30-second checker at glovrex.com/check.
Most of these gaps can't be closed by translation alone. 特商法 fields, JIS X 4051 typesetting, the IME-submit bugs that break Japanese text entry, procurement conventions — these need someone who has actually shipped to Japanese users, not a translated approximation. But you don't need me to start: run the four checks on your own product today. The demand for your tool in Japan is probably already sitting in your GitHub issues.
Scores and examples verified against live sites and public GitHub issues, 2026-06. Estimates of public signals, not claims about anyone's revenue or compliance. Corrections welcome: hello@glovrex.com.