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heir; inheritor
successor
社長が引退した後、長男が後継として会社を継いだ。
After the company president retired, his eldest son took over the company as heir.
後継を育てるには時間と根気が必要だ。
Raising a successor requires time and patience.
この農家には後継がおらず、廃業の危機にある。
This farm has no heir and faces the risk of closing down.