Japanese business writing runs on set phrases and careful levels of politeness, which can make polished human text and AI output look alike. Winston AI checks Japanese for signs of machine writing and highlights the sentences that read that way. Here's how mixed scripts, keigo and the business email affect what you see.
Three scripts, no spaces
A normal Japanese sentence can mix kanji, hiragana and katakana, plus Latin letters and numbers for product names and dates, with no spaces between words. Long words written in katakana, often borrowed from English, sit next to kanji compounds. None of that needs preparing on your side. Winston AI detects Japanese automatically, so paste text as-is, whether it comes from a web page, a PDF report or an email thread.
Keigo and the business email
Japanese business email follows a pattern most people learn on the job: お世話になっております to open, a clear statement of purpose, and よろしくお願いいたします to close, all in keigo. Writers move between teineigo (です and ます), sonkeigo (raising the other person) and kenjōgo (lowering oneself) depending on who they're writing to.
Because the formulas are so fixed, a human email and an AI-drafted one can share half their lines. The stock openings and closings tell you little either way. The body is where it counts: default AI output tends toward smooth, general statements, while a person writing to a real client usually refers to specific dates, orders or earlier conversations.
- Check whether highlights sit on the set phrases or on the actual content
- Compare with emails the same person sent before
- Ask about the draft before drawing any conclusion
The same applies to job applications. Entry sheets and 志望動機 (statements of motivation) are often polished with help from a career centre or a tool. Our page for recruiters covers how to use a score to plan interview questions rather than to screen people out.