Kouji Hiwatari is a Japanese actor and voice actor born on October 11, 1960, in Tokyo. He began his journey into acting after initially studying art at university, a path he chose over his childhood fascination with film. His entry into the performing arts was marked by persistence; after an initial rejection from the Bungakuza Acting Institute, he gained experience as a film extra through the Toei Tokyo Studio acting school. He was later accepted into the Bungakuza Acting Institute, which led him to leave university in his senior year to fully commit to acting. He joined the theater troupe Za Yōkigi na Shubidai in 1987 and has been affiliated with the talent agency Mouse Promotion since 2004.

Hiwatari has built a substantial career in anime voice acting, lending his voice to a wide array of characters across numerous popular series. He is perhaps most widely recognized by contemporary audiences for his role as Onyankopon in Attack on Titan The Final Season, a skilled pilot and key ally to the Scout Regiment. His other notable anime credits include roles in long-running and influential franchises such as various installments of Pretty Cure, including Fresh Pretty Cure and Yes! Pretty Cure 5, and My Hero Academia, where he voices Kyoka Jiro's father. He has also appeared in ARIA The ORIGINATION, Casshern Sins, Legend of the Galactic Heroes: Die Neue These, and Windy Tales.

Beyond anime, Hiwatari's career is characterized by its versatility across different media. He is an active stage actor with a repertoire that includes classical roles in Shakespearean plays such as Hamlet and Macbeth. He has also appeared in Japanese television dramas and films. Furthermore, he has a significant body of work in voice dubbing for foreign films and television series, providing the Japanese voice for characters in major productions like the Pirates of the Caribbean films, The Sound of Music, ER, and The Good Wife. His work in video games and radio programs further demonstrates the breadth of his performance career.