Yi Sung Sun (이성순, 李聖淳, February 29, 1916 – January 25, 1983), nicknamed Sirasoni(시라소니),^[1] was a South Korean street knight.^[2] He was born in 1916, in the North Korean city of Sinuiju.

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After the independence of Korea, Yi ran away to South Korea to join with his gangster friend Yi Hwa-ryong's gangs of Myeongdong. After the Korean War broke out, Yi worked in the Headquarters of the Intelligence Detachment. In 1953, the political hoodlum Yi Jung-jae lured Yi out and lynched him, making him Yi disabled. Yi left the gangs, and escorted Chang Myon and Shin Ik-Hee from political hoodlums.

• Portrayed by Jo Sang-goo in the 2002-2003 SBS TV series Rustic Period.