The less a map contains, the more it involves you. This is also true of PowerPoint presentations. (Above all, historical maps should not contain arrows.)
Looking at the Sea of Japan map (separate window), you think of the straits which Dutch, Russian and French sailors navigated; of the Jesuits whom the Japanese had confined to the mainland; of Peter the Great’s prospectors, Russian settlers, alarmed shoguns; wonder who, if anyone, ever travelled overland from the Strait of Tartary to Vladivostok; realise why North Korea is an unruly client of China, not Russia; ask yourself why such a small part of the Japanese population faces that sea; see what Japanese generals stared at in 1900: Korea, the colonial temptation; Manchuria, the sphere of influence (was that phrase already used?), separated from the sea only by a thin strip of Korea and Russia; Russia, the alien superpower whom they were about to defeat as they had already defeated their giant, enfeebled and estranged cultural parent China.