～にしろ／～にせよ— Whether One Way or Another

• 理由が何であるにせよ、遅刻は許されない。

  Riyuu ga nan de aru ni seyo, chikoku wa yurusarenai.

  Whatever the reason may be, being late is not acceptable.

  Concedes any possible reason; the conclusion holds regardless

• 行くにしろ行かないにしろ、返事だけはしなさい。

  Iku ni shiro ikanai ni shiro, henji dake wa shinasai.

  Whether you go or not, at least give a reply.

  Paired にしろ...にしろ lists both alternatives

• 冗談にせよ、言っていいことと悪いことがある。

  Joudan ni seyo, itte ii koto to warui koto ga aru.

  Even if it's a joke, there are things you should and shouldn't say.

  Noun 冗談 + にせよ concedes the 'joke' framing but still objects

• ・Register: formal/written; にせよ is the more literary of the two.
• ・Paired form (AにしろBにしろ) = 'whether A or B'; single form = 'even if'.
• ・Functionally the same as にしても but a step up in formality.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ～にしろ／～にせよ is tested against.

• ～上は — Now That the Die Is Cast
• ～ことなく — Without Ever
• ～ことになっている — It's The Rule
• ～つつある — In the Process of Changing
• ～において／～における — In; At; Regarding (Formal)
• ～に関して／～に関する — Regarding; Concerning
• ～に沿って — Following the Line
• ～につき — Per / Owing To (Formal Notice)