万まんが一いち

adverb

if by some chance; in the unlikely event

Used as an adverb to express a very low probability; often paired with conditional forms like ～たら, ～ば, or ～ても. The literal sense 'one in ten thousand' is rarely used in modern Japanese.

See also: 万一

• 万まんが一いち遅おくれそうなら、電でん話わしてください。

  If by any chance you think you'll be late, please call.

• 万まんが一いちのことがあっても、慌あわてないでください。

  Even if the worst should happen, please don't panic.

noun

emergency; worst-case scenario

Used as a noun, often in the phrase 万が一に備える (prepare for the worst). Implies an extremely unlikely but serious situation.

See also: 万一

• 万まんが一いちに備そなえて、保ほ険けんに入はいっておいたほうがいい。

  You should get insurance just in case (to prepare for the worst).