Is an electronically issued Covid testing certificate valid?

In order to avoid confusion in place such as airport check-in counters, you are kindly requested
to present the MHLW’s prescribed format in a paper form.
However, in some cases, due to unavoidable circumstances such as the situation in each
country/region or the time constraints of the person concerned, it may not be possible to obtain
a paper copy of a testing certificate. Thus, it is acceptable to present an electronically issued
testing certificate (hereinafter referred to as “electronic testing certificate”) when boarding an
aircraft or entering Japan.
A testing certificate in an electronic format shall be treated as a valid testing certificate if it can
be presented as an attachment to an e-mail or displayed items on mobile terminal using an
application, or as a printed document.
Moreover these electronic testing certificates can be treated as valid, only if the items of
certificates are visually confirmed and are the same items as on paper testing certificates.
Any format of electronic testing certificate, such as PDF, image, photograph, is acceptable.
Nevertheless, testing certificates in a variable media (such as Word, Excel, e-mail text message
body) in which the contents can be modified by the applicant are invalid. In addition, if items
necessary for confirming the validity of the testing certificate (such as personal information,
specimens and test methods) are unclear or blurred, such certificates are also regarded as invalid.
Please kindly note that Japanese and foreign nationals entering Japan from areas other than
those subject to landing refusal will be required to print out or send them to a designated e-mail
address for submission upon entry into Japan, and that foreign nationals entering Japan from
areas subject to landing refusal will be required to submit a printed copy at the immigration.

Information obtained from:  Ministry of Foreign Affairs of Japan Website