Japanese Foreign Ministry: All citizens and tourists entering the country must undergo a 14-day quarantine 
Japan due to the emergence of a new strain coronavirus omicron from December 1 cancels relaxed quarantine requirements for fully vaccinated citizens and foreigners with long-term visas or residence permits (residence permit). This is stated on the official website of the Ministry of Foreign Affairs of Japan.
All persons, including those who have been fully vaccinated and have the appropriate certificate, arriving in Japan from countries with an acute epidemiological situation will be required to undergo a mandatory two-week quarantine. The requirement for mandatory quarantine for three days in a special hotel is also returning.
In addition, the Japanese authorities are canceling the concessions introduced three weeks ago on the entry of foreigners on business and study visas.
New measures will be about a month – so much time is given by the authorities to obtain detailed information about the new strain of COVID-19. According to Japanese Prime Minister Fumio Kishida, this may take from two to three weeks to a month.
At the same time, the first suspicious case in Japan has already been discovered. A passenger arriving from Namibia tested positive for coronavirus. It is now being investigated whether this is an omicron infection.
Earlier it became known that Japan would close its borders to foreigners due to the spread of the omicron strain of COVID-19 in the world. The entry ban will take effect from November 30 and will affect all foreign citizens.