How to say "due" in Japanese

• 正式せいしきJLPT N3approx.Common
  na-adjective, no-adjectiveCovers 'due' in the sense of proper and official, as in due formalities: procedures carried out in the correct official form. Typical context: completing the formalities for a visa or a contract.
  彼女かのじょの服装ふくそうは正式せいしきなパーティーでは場違ばちがいだった。↗

  Her clothes were out of place at a formal party.
• 正当せいとうJLPT N1approx.Common
  na-adjective, nounCovers 'due' meaning just, right, or deserved — what is rightfully owed or legitimately claimed. Typical context: a justified demand or request, or the punishment someone deserves.
  先生せんせいは彼女かのじょに正当せいとうな取り扱とりあつかいをしなかった。↗

  The teacher didn't do her justice.

Use 正式 for 'due' meaning proper or official, as in due formalities, and 正当 for 'due' meaning just or deserved; neither fits the deadline sense of 'due', as in a payment due tomorrow.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 正式せいしきformal
• 正当せいとうjust
• 真まjust
• しかるべきproper