Cho Sang Gu

Ex-convict and Geu Ru's estranged uncle who becomes his guardian upon release from jail. He is blunt, smokes cigarettes, and moonlights as an underground MMA fighter. He was sent to jail after putting his protégé Su Cheol into a coma during a fight. Despite his background, he is still entrusted to take care of Geu Ru after his release, and is instructed stay and work with Geu Ru for a three-month probationary period. Although he initially does so for financial gain and appears to be ignorant of Geu Ru's condition, he slowly gets to know Geu Ru as they both work together as trauma cleaners for Move to Heaven, gaining a new outlook on life and allowing him to discover the truth about his half-brother and Geu Ru's father Jeong Woo, who he believes had abandoned him when he was still very young.

(Source: Wikipedia)