vintage incised pottery cups & saucers w/ Japanese character backstamp marks

Intriguing vintage pottery cups and saucers, marked only with Japanese characters on the bottom as shown. The saucers measure 4 3/4" in diameter. All four saucers look good, there is damage to the rims on two of the cups.

I have not been able to track down any information about this inscised technique artwork, or the exact vintage or origins of these pieces.

I love the white raised design against the latte coffee brown background, these look both very traditional and strikingly modern as the same time.