Grudge-laden Lackey

The Taesung Gang was everything to its boss, Kang Deokbae. But his golden days come to an end on his 50th birthday, when a rival mob ambushes the gang and fatally injures him. After entrusting Taesung to his loyal subordinates, Deokbae closes his eyes and wakes up 30 years later as Lee Taejun, a 23-year-old gangster! And upon learning that his gang is no longer the upright group it once was, Deokbae swears to set things right... even if he must destroy Taesung from the ground up.

(Source: Tapas)