Looking again at the site I referred to earlier, this mark is similar to other marks on Satsuma-ware
Japanese Satsuma Pottery
Look toward the bottom of the page. You will find a number of marks with the kanji for right, followed by a number. I'm tempted to say that the piece was originally part of a pair, and right marked the position of this piece, with the number being the number of sets produced... but this is out of my field so take that with a grain of salt.