On 30 October 2012, Sang-chu enlisted for mandatory military service for five weeks of basic training followed by 21 months as an active-duty soldier with the 306th draft in Uijeongbu, Gyeonggi Province, where he served along with Super Junior's leader Leeteuk until his discharge on 8 Aug 2014.

[2] In 2012, Sangchu had a cameo role as a 'muscle boy' student in the K-drama To the Beautiful You, in a bathroom scene with the lead role played by Sulli who was disguised as a boy.

[11] In April 2016, he portrayed a skilled pickpocket in the historical K-drama The Flower in Prison.

[12] Sangchu was under investigation for allegedly visiting a massage parlour, famous for prostitution, whilst on military duty[13][unreliable source?]

They allegedly visited several parlors that were closed before they found one that was open late.