The Regressed Son of a Duke is an Assassin

Cyan Vert, the illegitimate son of the Duke and the empire’s greatest assassin, is betrayed by the righteous brother whose shadow he’s always lived in. But just before the fatal blow strikes his throat, Cyan awakes to find he’s just a boy again. The young lord has been reborn, and this time, he’s not going to live in anyone’s shadow!

The Reborn Young Lord Is an Assassin; 회귀한 공작가의 막내도련님은 암살자; The Regressed Son of a Duke Is an Assassin; The Regressed Youngest Son of the Duke Is an Assassin; El asesino que retornó como el hijo del Duque; El pibe que retorna como el hijo menor; La venganza del asesino de la espada demoniaca; Вернувшийся младший сын герцога; Регрессировавший сын герцога; ลูกชายคนเล็กของดยุกคือมือสังหาร; 回帰した公爵家の末息子は暗殺者; 公爵家的重生暗杀者; 歸來的少爺是暗殺者; Hoegwihan Gongjakga ui Maknae Doryeon-nim eun Assassin