This uncommon, B&W post card of Esutoru Port, Karafuto Prefecture(present-day Sakhalin), Japan, was mailed to Yamagata, Prefecture, Japan, on April 26, 1915! The Japanese had taken over Karafuto during the Russo-Japan War(1904-1905). 

To continue, the blue, 1.5-Sen, Japanese definitive is in superb condition! The Japanese-language, CDS cancel from the  post office is quite good in many respects, but the name of the post office is hard to make out for sure. The sender was living in Ushiro County, Karafuto Pre., for sure, though.

Lastly, as for the post card, itself, it is in very good condition! It's very clean! There is very little wear and tear around the edges. Noted imperfections aside, considering that it's almost 109 years old, this relatively rare, Japanese post card sent from Karafuto Prefecture has survived the ravages of time very well!