口裏を合わせる

• Reading: くちうらをあわせる
• Romaji: kuchiura wo awaseru
• Kanji breakdown: 口 (kuchi) — mouth | 裏 (ura) — back, inside, hidden side | 合 (a) — to meet, align
• Pronunciation: /kɯ.tɕi.ɯ.ɾa o a.wa.se.ɾɯ/

Meaning

To get one's story straight; to collude on a shared account; to agree on a version of events beforehand.

An idiomatic expression using 口裏 (the back/inside of the mouth, figuratively 'the details of what one says') and 合わせる (to align, to match). The phrase implies coordination before a confrontation or inquiry, often carrying a negative connotation of deception or covering up. Used in legal, investigative, and interpersonal contexts.

Examples

1. 二人は事前に口裏を合わせていたようで、証言がぴったり一致していた。 The two of them appeared to have gotten their stories straight beforehand, as their testimonies matched perfectly.
2. 試験前に口裏を合わせて言い訳を準備したが、先生には全部お見通しだった。 They colluded on an excuse before the exam, but the teacher saw right through all of it.
3. 疑惑を持たれているのに口裏を合わせようとするのは、かえって怪しまれる。 Trying to get your stories straight when you're already under suspicion only makes you look more suspicious.

Usage Guide

Context: legal, investigation, conspiracy, workplace

Tone: negative

Origin & History

口裏 refers to the internal, hidden side of what one says. Combined with 合わせる (to align), the phrase evokes two parties quietly synchronising their stories so that the hidden seams are invisible to outsiders.

Cultural Context

Era: Modern

Generation: Adults

Social background: General