
Quick answer — Nobuaki Kanemitsu voices Dunston in Major S6, Katsuhiro Osada in Nodame Cantabile Finale, Keisuke Andou in Kimi ni Todoke: From Me to You and 20 more characters.
Nobuaki Kanemitsu voices Dunston (Major S6), Katsuhiro Osada (Nodame Cantabile Finale), Keisuke Andou (Kimi ni Todoke: From Me to You), Kuroma (Toradora!), Laurie Consabtier (An Observation Log of My Fiancée Who Calls Herself a Villainess), Takanori Kikuchi (And Yet The Town Moves), Tomoaki's Father (O Maidens in Your Savage Season), Anshou (Kusunoki's Garden of Gods) and 15 more.
Dunston is voiced in Japanese by Nobuaki Kanemitsu.