Kousaku Matsuda is a supporting character in the anime adaptation of Yawara! A Fashionable Judo Girl, later designated as a main role in the manga. He works as a sports reporter for the struggling newspaper Nikkan Every, a publication widely considered substandard within the industry. At the start of the story, Matsuda is around twenty-three to twenty-five years old and is depicted with black hair and black eyes. His physical appearance is that of a young adult male of Japanese nationality.

Matsuda’s personality is tenacious and single-minded. Initially, he feels unfulfilled by his work and is frustrated by the lack of excitement in his reporting assignments. This changes dramatically when he accidentally witnesses Yawara Inokuma using a judo throw to stop a fleeing thief. Recognizing the immense, hidden talent of a potential superstar, he becomes instantly captivated and makes it his mission to expose her abilities to the public. His early obsession manifests as a relentless, sometimes intrusive pursuit of the young judoka, repeatedly trying to trick or coerce her into revealing her skills. As the narrative progresses, however, his perspective softens considerably. After spending more time with Yawara and learning about her genuine desire for an ordinary life, his relentless journalistic ambition matures into a protective and supportive loyalty. He gradually shifts from being a sensationalist reporter to a trusted confidant and ally who respects her personal dreams.

His primary motivation is initially professional: he longs to publish a world-shaking scoop that will elevate his newspaper and give meaning to his career. This drive, however, intertwines with a deepening personal affection for Yawara herself. Over time, he falls in love with her, and much of his later behavior is motivated by a sincere wish to see her happy, even if that means shielding her from the very spotlight he once wanted to force upon her. He also develops a more genuine passion for covering the world of women’s judo as a sport, not merely as a vehicle for a story.

Matsuda serves a pivotal role in the story as the outside observer who first recognizes Yawara’s potential and, through his articles, repeatedly drags her unwillingly into the public eye. His initial articles in Nikkan Every catalyze a chain of events that forces Yawara into competition, despite her grandfather Jigorou’s own secretive agenda. As the series advances, he becomes her supporter and advisor, helping her navigate the pressures of fame, family expectations, and her own conflicting desires. He also functions as a rival in love to Shinnosuke Kazamatsuri, the charming judo heir. Beyond Yawara, his presence provides a lens through which the competitive judo world is explored from a sports journalist’s viewpoint.

His key relationships center on Yawara Inokuma, with whom he shares a complex bond that evolves from journalist-and-subject to genuine friendship and unspoken romantic tension. He acts as a foil to Yawara’s grandfather, Jigorou Inokuma, often clashing with the old master’s manipulative methods while sharing the common goal of seeing Yawara succeed. A significant secondary dynamic involves Kuniko Kaga, a younger fellow reporter at Nikkan Every who develops feelings for Matsuda. She becomes aware of his attachment to Yawara and initially engages in schemes to separate them, but later acts as a catalyst that helps the two draw closer. Matsuda also maintains a professional rapport with other characters in the judo community, such as Kaoru Hanazono and Fujiko Ito, though those interactions are less central.

The own series creator, Naoki Urasawa, described characters like Yawara and Matsuda as "very good supporting characters" and noted the difficulty he experiences when portraying strongly motivated leads, finding it easier to develop supporting figures. This self-assessment suggests that Matsuda's journey from a one-dimensional scoop-chaser to a multi-layered ally was a deliberate, challenging narrative choice that allowed him to grow beyond his initial archetype.

Matsuda’s development arcs from a dissatisfied newspaperman to a passionate journalist, and from a persistent nuisance to a devoted protector. In the early episodes he pulls stunts like chasing Yawara in disguise or staging situations to force her to use judo, but after understanding her genuine dislike of fame, he begins to intervene to protect her privacy. By the later portions of the story, he serves as an emotional anchor, reminding Yawara that her happiness matters more than any medal or title. This transformation into a selfless supporter highlights the series’ broader themes of balancing personal ambition with human connection.

His most notable abilities lie in his journalistic tenacity, resourcefulness, and powers of observation. He has a sharp eye for talent and a knack for crafting compelling sports stories, which gradually earns him respect even though his newspaper remains minor. He is not a judo practitioner himself and possesses no athletic prowess, but his determination to uncover the truth and his uncanny ability to appear wherever Yawara competes make him an ever-present force in her life. Ultimately, his greatest contribution is not a physical skill but the role he plays as the one person who persistently sees the real Yawara behind her prodigious strength.