Japan just started to accept foreign passport holders who have a residency status in Japan, so most likely people who hold some sort of visa and who actually live in Japan. They were talking about opening to business travel for some selected country, but nothing official yet.
So the current regulation is pretty much Japanese citizen or foreign residents that also have all the required paperwork (https://www.mofa.go.jp/ca/fna/page4e_001074.html) only.
I guess that it will take a while before they allow foreign tourist in.
The state of emergency in Japan was lifted across the entire country on May 25th, 2020. Strict coronavirus restrictions have been gradually reduced since, and most businesses in the country are now permitted to operate freely once again.
Nevertheless, citizens across Japan are still being advised to exercise social distancing measures and avoid crowded and poorly ventilated spaces.
Restrictions on domestic tourism within Japan and travel between prefectures have been lifted, although residents of Tokyo are still being advised not to undertake non-essential travel outside of the capital to avoid further spread of COVID-19 in the country.
The Japanese Ministry of Foreign Affairs has asked residents of Japan not to undertake any inessential overseas travel until otherwise advised.
Additionally, Japan has imposed entry restrictions for travelers coming from regions highly affected by the COVID-19 pandemic, as well as a mandatory quarantine for passengers arriving from some other territories.
However, a gradual reopening of Japanese borders is expected to begin soon, start with territories where COVID-19 has largely been contained, such as Australia and New Zealand, Priority will first be given to business and professional travelers. Access for students and tourists will then follow.
For more information regarding the current situation in Japan, you can visit this link https://www.jrailpass.com/blog/coronavirus-covid-19-advisory-info where you can also further be informed on what Countries and regions are banned to enter Japan as well as Visa Suspensions, etc.
Thank you :)