Tough as Iron (2013)

Gang-cheol is a legendary street fighter in Busan, who cleaned up his act to care for his sick mother. Things are going well for him, and he's happy in a budding relationship with Su-ji, vacationing in the seaside town. As their relationship grows, Gang-cheol is dragged into the criminal underworld when he sees Busan gangsters Sang-gon and Hwi-gon re-staging the accidental death of a Yakuza mobster as an accident and an old friend, Jong-su, gives him up to the Busan gang. Knowing he's desperate for money for his mother's operation, Sang-gon proposes that Gang-cheol works for him. Gang-cheol refuses, but when Jong-su gives the deed to Gang-cheol's how to Sang-gon as collateral for a private loan, Gang-cheol is left with no choice, but to bite the bullet.

Source: TMDb