
Quick answer — Kouji Takahashi voices Ash Blake in Dragonar Academy, Johann in Ascendance of a Bookworm Season 3, Eric Surt in K and 4 more characters.
Kouji Takahashi voices Ash Blake (Dragonar Academy), Johann (Ascendance of a Bookworm Season 3), Eric Surt (K), Loic Sleison (Outbreak Company), Eisuke Doudou (SERVAMP), Souichirou Fuji (Onee-chan ga Kita), Tatsuo Hori (Bungo and Alchemist -Gears of Judgement-).
Ash Blake is voiced in Japanese by Kouji Takahashi.