Why Japanese Character Counting is a Nightmare for Developers (and How to Solve It)

As developers, we often think of character counting as a simple string.length operation. However, when your application hits the Japanese market, this "simple" task becomes a complex maze of encodings, visual standards, and legacy system requirements. If you are working on localization (l10n), internationalization (i18n), or SEO for the Japanese market, here is what you need to know. 1. The Encoding Trap: UTF-8 vs. Shift-JIS While modern web standards favor UTF-8 (where a Japanese character is typically 3 bytes), many Japanese enterprise systems, government databases, and legacy banking platforms still use Shift-JIS . In Shift-JIS, full-width characters are exactly 2 bytes, and half-width characters are 1 byte. If your database has a strict byte limit based on Shift-JIS, a standard JavaScript character count will fail you, leading to data truncation or system errors. 2. Full-Width vs. Half-Width (Zen-kaku vs. Han-kaku) Japanese text often mixes: Full-width Kanji and Kana (Visual 1 char