Naega Wae Killer?!

'Joe', who unexpectedly became an Undercover agent, must complete this mission in order to move to his original goal, an office job. This is an undercover investigation into ‘Wild Dogs’, a vicious killer group under a criminal organization! In order to extract information from the fearsome killers, he disguised himself as a killer and went into hiding, but for some reason, Joe's reputation as a killer grows... A wild, comical undercover investigation!

(Source: Naver Webtoon, translated)