noun
Positive outcome or compensation for one's actions, often in a moral or karmic sense. Can be used in both concrete and abstract contexts.
善行には必ず報いがある。
Good deeds are always rewarded.
彼の努力の報いとして、昇進が決まった。
As a reward for his efforts, he was promoted.
noun
Negative consequence or punishment for one's actions, often implying a moral or karmic payback. Frequently used in phrases like 報いを受ける (to receive one's just deserts).
悪事の報いで、彼は刑務所に入った。
As retribution for his crimes, he went to prison.
自分のしたことの報いを受けるべきだ。
You should face the consequences of your actions.
Derived from the verb 報いる (mukuiru, 'to reward, to repay'). The noun form 報い carries the sense of recompense, both positive and negative.