
Quick answer — Katsumi Suzuki voices Tadashi Sakurai in GTO: Great Teacher Onizuka, Morioka Tomio in Tsurune, Hayao Kakizaki in Macross and 6 more characters.
Katsumi Suzuki voices Tadashi Sakurai (GTO: Great Teacher Onizuka), Morioka Tomio (Tsurune), Hayao Kakizaki (Macross), Warera Nantes (Macross), Murabito (Ninja Scroll), Umao (Kimagure Orange☆Road), Juubee Aoki (Let's Make a Mug Too 2), Grandpa Higurashi (Yashahime: Princess Half-Demon) and 1 more.
Tadashi Sakurai is voiced in Japanese by Katsumi Suzuki.