居い住ずまいを正ただす

expression, godan verb (-su)

sit up straight; straighten one's posture; compose oneself

Used when someone corrects their slouching or casual sitting position to a more formal, attentive posture, often in a situation requiring respect or seriousness.

• 面めん接せつ官かんが入はいってきたので、居い住ずまいを正ただした。

  When the interviewer entered, I sat up straight.

• 先せん生せいの話はなしを聞きくときは、居い住ずまいを正ただしなさい。

  When listening to the teacher, sit up properly.