The conditions and requirements for foreign participants to enter Japan changed on October 11, 2022.

The visa exemption measures for ordinary passport holders of 68 countries/regions (see the list) for short term (< 90 days) stay for business/conference, which had been temporarily suspended, have been resumed from October 11, 2022.

The list of visa exemption countries/regions :
https://www.mofa.go.jp/j_info/visit/visa/short/novisa.html

NOTE!! The participants entering Japan with Brazilian passports are still required to have visas.

All foreign participants entering Japan must submit a completed questionnaire, and either a vaccination certificate or a negative COVID-19 test result (performed and issued within 72 hours before departure).

For details of a vaccination certificate and a negative COVID-19 test, see the webpage below of the Ministry of Health, Labour and Welfare.
https://www.mhlw.go.jp/stf/covid-19/bordercontrol.html

Foreign participants are strongly encouraged to use Fast Track to simplify Japanese entry procedures and smoothly enter Japan.

To use Fast Track you must pre-register via MySOS Web (online) or the MySOS app. For details, see below.
https://www.hco.mhlw.go.jp/en/