Update 2022-03-02 (2): Since Wednesday (1 March), international business travellers are allowed to enter Japan again. The quarantine is only 3 (full) days and can be completely bypassed with the proof of a booster vaccination (3 vaccine doses). Tourist entries are still not possible.
Update 2022-03-02 (1) – Official note issued by the RKI: In its latest update from Tuesday (1 March), the Robert Koch Institute (RKI) removed Japan from the list of international high-risk areas with effect from Thursday (3 March). Therefore, the travel warning by the Federal Foreign Office for Japan will be lifted.