Detect AI in Japanese text.

• 1Keigo (honorific) formality system inconsistently applied
• 2Sentence-final particle usage less natural than typical Japanese
• 3Three-script (kanji/hiragana/katakana) mixing sometimes mechanical
• 4Topic-comment structure defaults to subject-predicate AI patterns

Japanese AI detection, in detail.

Japanese AI detection is shaped by the language's three-script system (kanji, hiragana, katakana) and its complex honorific (keigo) system. AI-generated Japanese often deploys kanji at higher density than typical Japanese writing, mixes script choices in ways that don't match conventional usage (e.g., using kanji for words typically written in hiragana for warmth), and produces keigo constructions that are grammatically correct but stylistically unusual. AI Checker reaches 91-93% accuracy on unedited Japanese AI output, with rapidly improving coverage as we expand training data. The strongest Japanese-specific signal is sentence-final particle usage — particles like ね, よ, and です/だ choices encode register and speaker stance in ways that AI Japanese often misjudges. For Japanese business and academic contexts where keigo precision matters, our enterprise tier provides specialized calibration. Japanese detection is one of our most active development areas given growing demand from Japanese publishers and educators.

Japanese detection in depth.

Japanese AI detection is among the technically most challenging cases in our model lineup because Japanese encodes more dimensions of meaning in surface-level writing choices than most languages. The three-script system (kanji for Sino-Japanese vocabulary and most content words, hiragana for grammatical particles and native Japanese vocabulary, katakana for foreign loanwords and emphasis) gives writers continuous choices that encode tone, register, and reader-relationship. AI Japanese tends to deploy kanji at higher density than typical Japanese writing — AI models trained on academic and literary corpora over-default to kanji even in contexts where native writers would write the same word in hiragana for warmth or accessibility. AI Japanese also occasionally writes native Japanese words in kanji forms that are technically correct but archaic or unusual in modern usage. The keigo (honorific) system is the second major signal. Japanese has multiple distinct registers (sonkeigo for elevating others, kenjōgo for humbling self, teineigo for general politeness) and uses them based on subtle social context that AI models handle imperfectly. AI Japanese sometimes produces keigo constructions that are grammatically correct but stylistically wrong for the context, or mixes registers in ways native writers naturally avoid. Sentence-final particles (ね, よ, よね, わ, さ, ぞ, the desu/da copula choice) encode register and speaker stance with subtle distinctions that AI Japanese frequently misjudges. AI Checker reaches 91-93% accuracy on unedited Japanese AI output across GPT-4, Claude, and Gemini. Detection is one of our most active development areas given growing demand from Japanese publishers, educators, and corporate communications teams. Our enterprise tier provides specialized calibration for business-Japanese contexts where keigo precision is critical (corporate correspondence, legal documents, formal academic writing) — these contexts have native register baselines that differ enough from general Japanese to warrant separate models.

Detection by model, audience, and comparison.