This as part of the news earlier on potentially stopping international arrivals:

Via Nikkie :

  • The suspension will be in place at least during Japan's state of emergency, which will start as early as Thursday and is expected to last for about a month.
  • On Dec. 28, the Japanese government halted new entries of foreign nationals until the end of January in an effort to halt the spread of the new coronavirus variant that is growing more prevalent in the U.K. and other countries. But entry through the business travel arrangements with the 11 countries and regions was permitted as an exception.

Link for more (may be gated)