Square Japanese Heavy Black Cast Iron

Imprinted on Bottom JAPAN 2- Piece I am not sure exactly what this piece is but from what I can tell it could be a Square Heavy Black Cast Iron Teapot Warmer or a decorative Steamer for use on a wood burning stove Also could be a coil burner for incense or to repel mosquitos or an ash tray Square Base and 4"x4" Grid Insert Grill
Please view actual photos. This looks in good condition. Some nicks. Shows some usage and age.
If you know exactly what this item is, I am interested in knowing. I picked it up mostly due to its novelty, and a desire to know what its purpose is.