
Quick answer — Yoku Shioya voices Ryouta Miyagi in Slam Dunk, Cosmo Yuuki in Space Runaway Ideon, Jirou Shioya in Tomorrow's Joe 2 and 9 more characters.
Yoku Shioya voices Ryouta Miyagi (Slam Dunk), Cosmo Yuuki (Space Runaway Ideon), Jirou Shioya (Tomorrow's Joe 2), Takao Shibuya (Perfect Blue), Saku (Future Boy Conan), Will A. Zeppeli (JoJo's Bizarre Adventure (TV)), Edward Colombo (Kindaichi Shounen no Jikenbo (TV)), Noir (KIRA KIRA☆PRECURE A LA MODE) and 4 more.
Ryouta Miyagi is voiced in Japanese by Yoku Shioya.