I don't know if Keigo knows this particular 
seller or not, however some sellers on Yahoo 
Japan do end early if the bidding gets to a point 
they are content with, even if they do not have a 
buy price listed on the auction.  First things 
first (and I'm not necessarily saying this was 
the case on this particular auction, I don't know 
the number, but you ought to check)  Look at the 
description and where the "seller will not ship 
internatiionally" bit is usually written.  
Sometimes something that translates 
into "sometimes it ends early" or something 
equivalent depending on what translation utility 
you are using, is also written there.  This means 
that the seller stated clearly in the auction 
terms that they might end it early.  That may or 
may not be the case for this auction but it's 
worth checking.