Gen Shishio's unnamed mother appears very briefly in the series.
She is a woman of average height with black hair.
After young Gen gravely injured someone from the neighborhood, his parents and Ryo went to apologize, leaving Gen's brothers to capture him. Instead, Gen overpowered them, leaving them wounded and traumatized. Worried that he had become too dangerous, Gen's parents decided to send him away to the Shadow Organization for training.