Matsuda is one of Issei's best friends who made up the "Perverted Trio" (変態三人組 Hentai San'nin-gumi), a trio of the biggest perverts at the Academy, and is a self-proclaimed lolicon. Matsuda's nicknames are "Perverted Baldy" (エロ坊主 Ero-bōzu) and "Sexual Harassment Papparazzi (セクハラパパラッチ Sekuhara Paparatchi). Matsuda is a former jock and school sports star. He and Motohama are jealous of Issei's relationship with the Occult Research Club, and constantly spreads bad rumors about Issei, such as Issei being a sadist who blackmailed Rias and Akeno into doing sexual acts. He does not know that Issei and the Occult Research Club members are Devils.

(Source: High School DxD Wikia)