万一 (if by chance)
grammar90 sentences
The adverb 万一 ('if by some chance / in the unlikely event that') — literally 'one in ten thousand.' Sets a low-probability hypothetical, almost always paired with a たら/ば/なら conditional clause. The emphatic variant 万が一 ('in one in ten thousand') inserts the particle が for slightly more measured weight; both forms function identically.