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opposite side; reverse
(but) on the other hand; though; although; while
彼は私にとって反面教師だ。
He serves as a negative example for me.
表が終わったら反面も確認してください。
After the front, please check the reverse side too.
成功の裏には反面に多くの失敗が隠れていることが多い。
Behind success, many failures are often hidden on the other side.