Yūki Masuda is a Japanese actor and voice artist born on September 12, 1979, in the Tokyo Metropolitan area. His career began in the early 1990s, with one of his first roles being Tafuru in the 1992 anime The Little Twins. He achieved a significant breakthrough in 2004 when he was cast as Masaharu Niō in the television adaptation of The Prince of Tennis, a role that made him a fan favorite and one he has since reprised in numerous original video animations, feature films, and stage recordings associated with the franchise.

Throughout his career, Masuda has built an extensive filmography across anime, video games, and dubbed foreign productions. Beyond his iconic role in The Prince of Tennis, his notable anime roles include Daichi Misawa in Yu-Gi-Oh! GX, Fujimaki in Angel Beats!, Jun Isurugi in True Tears, G. in Reborn!, Riku Kaitani in Eyeshield 21, and Breo in Yu-Gi-Oh! 5D's. He also provided the voice for Kyoshiro in Ginga Densetsu Weed, Takahiro in Examurai Sengoku, and Yōji Sugawa in the short series Koitabi ~True Tours Nanto.

In the realm of video games, Masuda is well-known as the Japanese voice of Espio the Chameleon in the Sonic the Hedgehog series, a role he first took on in Sonic Heroes in 2003 and has continued to voice in many subsequent entries, including Shadow the Hedgehog, Sonic Colors, Sonic Forces, and Sonic x Shadow Generations. He has also voiced his Prince of Tennis and Yu-Gi-Oh! characters in various games based on those series.

Masuda’s work extends to live-action and stage performances. He played Hiroshi Kuronaga in the 2000 dystopian thriller Battle Royale. His stage career includes participation in several 2.5-dimensional musicals, notably the live series for The Prince of Tennis.