What has happened in the Japanese local board is that nearly all the awarded sMerit is being done basically by two people. Both of these have dropped radically (not nullified) the number of sent sMerits to the Local board (and in general) over the months of August and September 2018, therefore making a large dent on the Receiver’s side of the local board.
Obviously we do know the reasons (lack of sMerit, pause from the site, lack of interesting posts, etc.), but in cases such as this, where sMerit awarding is in the hands of one or two, any bump on the road is highly noticeable.

What I have seen is that there is a strong decrease in the number of posts over time in the Japanese local board:
There is obviously a correlation there, but which is the main driver of it all I cannot tell (less posts because there is less merits and less incentive, or less posts and therefore likely less to merit on the whole).