Vintage 1940's Japan Blue Willow mustard/ Jam Jar with attached undertray/No Lid  This piece is in very good condition with no chips or cracks but has some crazing and stains on back as shown in photo. 
  
It is a very scares item and if you have the lid it would be a wonderful piece to add to your collection. 
   It could be used for some condiments for the table with no lid such as packets of  sweetners,small amounts of jelly for breakfast, candies,etc.