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Description
Nanjirou Echizen is the father of the series' protagonist, Ryoma Echizen. He is a former professional tennis player who was known during his active years as Samurai Nanjirou or the Samurai from the Land of the Sakura, a title earned for his invincible skill on the court. He remains undefeated in his professional career, compiling a record of thirty-seven wins and zero losses, and was only one match away from achieving a Grand Slam title before unexpectedly retiring. The primary reason for his retirement was his wish to devote his time to teaching his son, Ryoma, how to play tennis from a very young age.

Nanjirou began his tennis journey as a junior high student at Seishun Academy, where he was trained by Sumire Ryuzaki, the future coach of the Seigaku tennis club. During his high school years, his natural talent became evident when he independently developed a technique called Nitouryuu, or Two Sword Style, to compensate for a weak backhand. This technique allows him to use either his left or right hand to return shots, making him ambidextrous on the court. After leaving Japan, he turned professional and quickly rose to the top of the tennis world, but he walked away from the sport at its peak.

In terms of personality, Nanjirou is laid-back, carefree, and often behaves in a childish and shamelessly perverted manner. He spends much of his time lounging around the house, reading magazines featuring scantily clad women, and teasing his family. This eccentric and brash demeanor stands in stark contrast to his son Ryoma's quiet, aloof, and socially dense attitude. Despite his eccentricity, Nanjirou is fiercely dedicated to Ryoma's development as a tennis player. His motivation is not merely to see his son succeed but to cultivate Ryoma's full potential so that he can take over the title of the strongest tennis player in the world and eventually become strong enough to defeat his own father.

Nanjirou's role in the story is primarily that of a background figure and a guiding force for Ryoma. He is the original source of many of the techniques Ryoma later masters, and he continues to push his son through unconventional training methods, such as using sticks and rocks as rackets and balls or training behind a waterfall. The Seigaku tennis team regulars are generally unaware that he is Ryoma's famous father; because of his odd behavior, they often treat him as a suspicious person whenever he appears. In later parts of the series, he takes on a coaching role for the Spanish national team in the U-17 World Cup, applying his expertise on an international stage.

His most significant relationship is with his son, Ryoma. Nanjirou has been Ryoma's tennis mentor since Ryoma was two years old. Their relationship is a mix of training master and student, with Nanjirou often using psychological provocation to stimulate growth. He is married to Rinko Echizen, a sweet-tempered attorney whom he met in the United States shortly after arriving to become a professional. He stood up for her against an abusive coach, and the two eventually married. He also has an adoptive son, Ryoga Echizen, in a non-canon movie, and a niece named Nanako Meino.

Nanjirou's notable abilities are among the most advanced in the series. He is an all-rounder who can play with either hand. His signature techniques include a modified Twist Serve that bounces to the side rather than toward the face; the Nanjirou Zone, a perfected version of the Tezuka Zone that draws all returns toward him with applied spin, allowing him to keep one foot planted; and Teni Muhou no Kiwami, or the Pinnacle of Perfection, which is the last door of the Muga no Kyouchi state. This state unleashes his full potential by allowing him to enjoy tennis with a pure mindset, enhancing all abilities and granting immunity to mental attacks. He also uses a one-footed split step for exceptional balance and reflexes, and he can enhance his concentration by closing his eyes during play. These skills, combined with his undefeated professional record, establish him as a legendary figure within the world of the series.