Sook Ching is a Chinese term meaning "purge through cleansing". The Japanese term for the operation was Dai Kensho, meaning “great inspection”.
Operation Sook Ching was a Japanese military operation aimed at purging or eliminating anti-Japanese elements from the Chinese community in Singapore. From 21 February to 4 March 1942, Chinese males between the ages of 18 and 50 were summoned to various mass screening centres and those suspected of being anti-Japanese were executed.
http://eresources.nlb.gov.sg/infopedia/articles/SIP_40_2005-01-24.html https://en.wikipedia.org/wiki/Sook_Ching