In case you missed it, Eamonn had the data release earlier in the day here. The core reading came in at 4.0% y/y, which is the highest since April 1982 with the core-core reading rising to 2.7% y/y in December, up from 2.5% y/y in November.
While the report only measures inflation in Tokyo, it very much presents the likelihood that overall inflation in Japan had stayed above the 2% target by the BOJ through December.
The Japanese central bank will announce their next policy decision on 18 January and while policymakers aren't likely to spring another surprise on markets, it is widely expected that they will raise their inflation forecasts at least.
However, as long as inflation data continues to show up like what we saw today, it will be harder and harder for the BOJ to keep ignoring the prospects of having to shift their policy stance.