Magnetic north is well south of polar north, and it has been moving east around a quarter mile a year for a long time. That is why Japan has “moved” closer to magnetic north: The pole is the thing that is moving
1. It looks like the pole is moving west (away from North America and towards Asia), not east.
2. But “latitude” is North/South, not east west; and the comment in the article said in 620 Japan was at 33 degrees magnetic latitude and is now at 25 degrees magnetic latitude - that is 8 degrees closer to magnetic north - but at least going back to 1590, in the link you gave us, I see no such movement of Japan closer to magnetic north, or magnetic north moving closer to Japan in latitude; though it appears to be moving closer to Japan in magnetic longitude.
3. Either there has been much greater LATITUDINAL change in the magnetic field from 610 to today that explains the change mentioned in the article, or there must be some other explanation. The chart from NASA does not explain the change mentioned in the article.