
Quick answer — Yuuji Takada voices Tatsumi Saiga in Speed Grapher, Frank in Argento Soma, Kyoushiro Toudou in Code Geass: Lelouch of the Rebellion and 7 more characters.
Yuuji Takada voices Tatsumi Saiga (Speed Grapher), Frank (Argento Soma), Kyoushiro Toudou (Code Geass: Lelouch of the Rebellion), Kansuke Yamato (Detective Conan: The Raven Chaser), Martin Zigmar (s-CRY-ed), Kazukiyo Gowa (Gasaraki), Yuri Leonov (Argento Soma), Keith (Popotan) and 2 more.
Tatsumi Saiga is voiced in Japanese by Yuuji Takada.