This 19th C Japanese Square Pottery Tea Pot was surely not made for export...it has a Mingei, or folk art look which is usually appreciated more in Japan than in the West. The body is covered with dark brown globules of glaze.
According to Sandra Andracht in the book "Treasury of Satsuma" , "Pieces of this type and age are attributed to the productions of the Ryumonji kilns". See a similar example on page 138 of the book.
Excellent condition: no chips no cracks, no repairs. It is large: about 7" long and 4 1/4" high (NOT including the basketry handle).