While travelers from many countries can visit Tokyo and Japan with relative ease for 90 days on a tourist visa, make sure you follow the official Japanese government visa and immigration guidelines to ensure that you can enter the country legally. If you are from a country that requires a visa for entry into Japan—even for a short stay—be sure to follow the required procedures.
https://www.mofa.go.jp/about/emb_cons/mofaserv.html
Please look at the list of the countries that have the visa exemption
agreement with Japan. If your country is included in the
list, you usually do not need to apply for an entry visa
to Japan.
If your country is not included in the list, you need to
obtain a short-term stay visa (“tanki-shouyou visa” in
Japanese) from the embassy of Japan in your country.
Read carefully the Japanese visa guide provided by the
ministry of foreign affairs. For entry into Japan, a
VISA may be required for ICMM 2020 attendees from some
countries. Please make sure whether you need to apply
for a VISA or not on the web site of Ministry of Foreign
Affairs of Japan at :
http://www.mofa.go.jp/j_info/visit/visa/index.html