Quick answer — Hiromi Ootsuda voices Kouji Kaminagi in Zegapain, Iwao Tamura in Oreimo, Harue Kasuga in We Without Wings – Under the Innocent Sky.
Hiromi Ootsuda voices Kouji Kaminagi (Zegapain), Iwao Tamura (Oreimo), Harue Kasuga (We Without Wings – Under the Innocent Sky).
Kouji Kaminagi is voiced in Japanese by Hiromi Ootsuda.
