Usage patterns
〈人〉の後任になるto become someone's successor
It was decided that I would become Mr. Tanaka's successor.
後任を決めるto decide on a successor
The board of directors decided on a new successor.
後任に〈人〉を選ぶto choose someone as the successor
The president chose a young employee as the successor.
〈人〉の後任としてas someone's successor
He took up the post as the former manager's successor.
