With effect of 24 July 2020, the Ministry of Justice has added 17 countries to the ban list of countries from which the entry to Japan is principally prohibited. The complete ban list in English can be found here:
Foreign residents with a permanent resident visa or spouse visa who have departed from Japan to a country before it was included in the ban list benefit from a general exemption according to which the direct reentry to Japan from such country is principally permitted.
For travels to most European countries, the latest possible departure date to benefit from this exemption was 2 April 2020, for the 17 newly added countries 23 July 2020. Condition precedent to benefit from this exemption is that the departure form handed over to the immigration officer upon departure from Japan indicates that a reentry to Japan is intended.
Except for the aforementioned general exemption, a reentry to Japan from a country on the ban list is only feasible based on individual circumstances requiring particular humanitarian considerations, which are admitted only in certain exceptional cases, but are principally available for all foreigners with middle-to long-term visa with re-entry permit.
General information on the available exemptions can be found here.