TOKYO, April 20 (Reuters) - Japanese shares fell on Tuesday by their most in a month, weighed down by worries that possible reintroduction of COVID-19 lockdowns in the country’s biggest cities would slow the economic recovery. Selling was seen across almost all sectors, with only one of the Tokyo Stock Exchange’s 33 industry sub-indexes closing higher and just 16 stocks up on the benchmark Nikkei share average. The Nikkei settled down 1.97% at 29,100.38, its worst since March 24, while the broader Topix dropped 1.55% to 1,926.25 in its biggest slide in four weeks. “It’s just like the decline is bringing another sell-off today,” said Shoichi Arisawa, general manager of the investment research department at IwaiCosmo Securities. “There is a concern about virus resurgence not only in Japan but also in other countries. Investors are becoming cautious about an economic reopening, particularly since many Japanese companies are sensitive to the global economy.” Tokyo and Osaka may slide back into states of emergency due to a resurgence in COVID-19 cases. Japan this month put these prefectures as well as others under “quasi-states of emergency” but those measures have done little to reverse the trend so far. Index heavyweights Fast Retailing, known for its Uniqlo clothing brand, fell 2.17%, while SoftBank Group lost 1.84%. Semiconductor-related stocks tracked their U.S. peers lower, with Tokyo Electron falling 2.3%, Advantest dropping 3.2% and Murata Manufacturing losing 1.58%. The top percentage losers on the Nikkei index were Marui Group Co Ltd, down 5.82%, followed by Dentsu Group Inc , losing 4.46%, and Daikin Industries Ltd, down by 4.28%. The biggest percentage gainers in the index were Kawasaki Kisen Kaisha Ltd, up 2.19%, followed by Mitsui OSK Lines Ltd, gaining 1.66%, and Oji Holdings Corp , up by 1.4%. The volume of shares traded on the Tokyo Stock Exchange’s main board was 1.09 billion, compared with the average of 1.29 billion in the past 30 days. (Reporting by Junko Fujita and Stanley White; Editing by Subhranshu Sahu)