In this case karafuto means the region and attached islands south of the fifty northern latitude on sakhalin (so-called southern sakhalin ), which was incorporated into japan through the treaty of portsmouth . この場合、樺太とは樺太の内、ポーツマス条約により日本へと編入された50度線以南の地域(いわゆる南樺太)及びその付属島嶼を指す。