
Quick answer — Yousuke Oumomo voices Koga Tsukishima in The Most Notorious "Talker" Runs the World's Greatest Clan, Zach in A Journey Through Another World: Raising Kids While Adventuring.
Yousuke Oumomo voices Koga Tsukishima (The Most Notorious "Talker" Runs the World's Greatest Clan), Zach (A Journey Through Another World: Raising Kids While Adventuring).
Koga Tsukishima is voiced in Japanese by Yousuke Oumomo.