Ryoga was first introduced in the series in the Tennis no Ouji-sama: Futari no Samurai - The First Game movie and was introduced into the manga later in Shin Tennis no Ouji-sama. Ryoga is the adopted son of Nanjiro Echizen, a former professional tennis player. He bears a strong resemblance to Ryoma with his hazel eyes (anime) and black-green hair. While the Echizen family were in America, Ryoga was taken in by Nanjiro and lived with them for a time. His tennis technique is modeled on that of Nanjiro. When he left the Echizen's home, he just wandered around until the evil billionaire Sakurafubuki Hikomaro hired him. In the flashbacks, it showed that he was rather close to Ryoma. At first he said that Ryoma's tennis was awful (which was true when he was about five or so). It was shown that Ryoga's skills were far superior, but as Ryoma continued to improve, Ryoga began spending more time with him.