Black Jack: Obaa-chan

After bringing the Shimizu family back to their home when their car broke down, Black Jack & Pinoko are introduced to Yoshiko, the grandmother of the family who's constantly asking for money & calls out Black Jack for his notoriously high fees to perform surgery. The truth of the matter, though, is that Yoshiko spends all her money on paying back an old debt to a doctor that saved her son's life, and when Yoshiko suffers from a fall her son is tested by Black Jack to see if he'd be willing to be in debt to pay off her mother's surgery. (Source: ANN)