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childhood friend; friend from infancy; old playmate
幼馴染みと久しぶりに会った。
I met my childhood friend for the first time in a long while.
彼とは幼馴染みで、何でも話せる関係だ。
He and I are childhood friends, and we can talk about anything.
幼馴染みの結婚式に出席するために遠くから駆けつけた。
I rushed from far away to attend my childhood friend's wedding.