The number of overseas tourists visiting Japan plunged 27.8 per cent from the previous year to 6.2 million in 2011, the sharpest drop on record, in the wake of the March 11 earthquake, tsunami and subsequent nuclear disaster, dpa quoted an industry group as saying Friday. The Japan National Tourist Organization said the yen's appreciation against major currencies was also responsible for the drop as a strong yen makes travelling to the country more costly. The number of tourists from South Korea, the biggest market, plummeted 32 per cent to 1.66 million, making up 26.7 per cent of the total, while visitors from China, the second-largest market, dropped 26.1 per cent to 1.04 million, accounting for 16.8 per cent of the total. The twin natural disasters struck north-eastern Japan on March 11, and triggered the nuclear crisis at the Fukushima Daiichi Nuclear Power Station. A series of fires and blasts led to the massive release of radioactive substances.