The is a post given to a minister of state designated by the prime minister of Japan to temporarily perform the prime minister's duties when they are not able to. The prime minister does not have to designate a successor, and as such the position is not always filled.
The position has been vacant since 4 October 2021, but the most recent, and longest serving, deputy prime minister was Tarà  Asà Â, who served as minister of finance concurrently. The deputy prime minister only exercises the functions of prime minister until the National Diet selects a new prime minister.