There seems to be conflicting advice on the official Ministry of Foreign Affairs website:
https://www.mofa.go.jp/ca/fna/page25e_000334.html
says it is necessary to present a certificate of inspection from within 72 hours before departure, but:
https://www.mhlw.go.jp/stf/covid-19/border_test.html
implies that this requirement is waived for 3-times vaccinated folk. There were some newspaper articles suggesting the same thing has applied since 7 September 2022.
What is the reality on the ground?
TIMATIC, which is what airlines go off on border requirements states :
Emphasis mine
Passengers must have a negative COVID-19 test result. Tests accepted are: CLEIA/ECLIA quantitative antigen test, LAMP, NEAR, Next Generation Sequence, PCR, RT-PCR, Smart Amp, TMA or TRC. The test must be taken at most 72 hours before departure from the first embarkation point, and the test certificate must be in English. The test certificate must also specify that the test is based on a "nasopharyngeal swab", or "saliva", or "nasopharyngeal and oropharyngeal swab". A "nasal swab" is also accepted if the test type is LAMP, NEAR, PCR, RT-PCR, Smart Amp, TMA or TRC. Details can be found at https://www.mhlw.go.jp/stf/covid-19/border_test.html and https://www.mhlw.go.jp/content/000905811.pdf .
This does not apply to passengers with a COVID-19 vaccination certificate showing that they were fully vaccinated and received a booster dose. Vaccines accepted are: AstraZeneca (Vaxzevria), Covaxin, Covovax, Janssen, Moderna (Spikevax), Nuvaxovid (Novavax) and Pfizer-BioNTech (Comirnaty). A combination of vaccines is accepted. The certificate must be in English, Japanese or accompanied by a certified English or Japanese translation. This exemption also applies to their accompanying children under 18 years.
This does not apply to passengers younger than 6 or 7 years depending on the school starting age in the country where they reside. More details can be found at: https://www.theglobaleconomy.com/rankings/Primary_school_starting_age/
This does not apply to US military personnel, civilian personnel, and their dependents. They must have SOFA status and have the required documents stipulated in Article IX of the US-Japan Status of Forces Agreement.
This does not apply to passengers with a consular letter specifying why the test could not be taken.
Passengers could be subject to a COVID-19 test upon arrival and quarantine for 3 days. Details can be found at https://www.mhlw.go.jp/stf/covid-19/bordercontrol.html and https://www.mhlw.go.jp/content/000945853.pdf
Passengers must complete a "Quarantine Questionnaire" through the MySOS app or at https://arqs-qa.followup.mhlw.go.jp/ . This will generate a QR code which must be presented upon arrival.
Passengers must install the "MySOS" mobile app before departure or upon arrival. More details can be found at https://www.hco.mhlw.go.jp/fasttrack/en/
So, as of 17 September, no airlines will ever let you board without a conforming COVID Test if you aren't vaccinated with 3 doses.
You don't need the test if you are vaccinated
