Cape Sōya.

“The Monument of the Northernmost Point of Japan is at the cape, although the true northernmost point under Japanese control is a small deserted island called Bentenjima, 1 kilometre (3,300 ft) northwest. Since the cape is just 43 kilometres (27 mi) away across La Perouse Strait from Cape Crillon, Sakhalin Island, Russia, it is possible to catch a glimpse of the island of Sakhalin on a clear day.”