Ryōji Sekiguchi is a Japanese voice actor born on October 25, 1970, in Kanagawa Prefecture, Japan. He is affiliated with the talent management firm Mausu Promotion, an agency he has been with since 1993 following its predecessor, the former Tokyo Actor's Consumer's Cooperative Society.

Sekiguchi pursued his interest in voice acting by enrolling at the Tokyo Announce Gakuin, also known as the Tokyo College of Announcement, from which he graduated in 1991. He subsequently entered the training school operated by the talent agency now known as Mausu Promotion, officially joining the agency in 1993 and beginning his professional career.

His career encompasses a wide range of roles in anime, video games, and dubbing for foreign media. In television animation, Sekiguchi is recognized for his portrayal of the character Toa in the long-running series Fairy Tail, as well as for his role as Jin Matsui in the classic series Yu Yu Hakusho. Other notable anime credits include parts in Concrete Revolutio ~Choujin Gensou~ The Last Song as Jonathan Morrel, and a role in Ushio & Tora as the father of Giyō and Ketsumei, Zhang Peng.

In the realm of video games, Sekiguchi has had recurring collaborations with the developer Shūhō Imai, particularly within the Tokyo Majin Gakuen series. He voiced the characters Hisui Kagetsu, Raijin Amemiya, and Hayato Kurosaki in Tokyo Majin Gakuen Kenpūchō, and later took on the roles of Kyūdō Kuguri, Jūrōta, and Nagi in Tokyo Majin Gakuen Hōhōchō. His game credits also include the role of Ryōma Togawa in the PlayStation 2 title九龙妖魔学園記 and Kosame Shōgun in the PlayStation 3 game 魔都紅色幽撃隊.

Sekiguchi has also contributed to original video animation projects and has been active in the dubbing of foreign films and television series. His work in audio dramas includes performances in various BLCDs and drama CDs related to the game franchises he has been involved with.