Ryuken Ishida is Uryuu Ishida's father and a formidable Quincy in his own right. Despite his immense power, he considers Quincy practices a waste of time. He acknowledges that while his son possesses the heart of a Quincy, he himself holds the true power. During his son's training to regain his Quincy abilities, Ryuken promises to train him but demands that Uryuu sever his friendship with Ichigo.
Although he refrains from participating in Quincy activities, Ryuken openly expresses his disdain for Shinigami. It is revealed that he knew Ichigo's father, Isshin, in the past. The end-of-episode clips often show them together, usually ending with Ryuken using his Quincy powers to shoot arrows at Isshin after being teased or shown pictures from their shared past. Both men are doctors; Ryuken runs a hospital, while Isshin operates a clinic.
