
Quick answer — Tamotsu Nishiwaki voices Butter in Kaiba, Nezumi in ONE PIECE: Episode of Nami - Koukaishi no Namida to Nakama no Kizuna, Shingo Yuuki in Kaze no Stigma.
Tamotsu Nishiwaki voices Butter (Kaiba), Nezumi (ONE PIECE: Episode of Nami - Koukaishi no Namida to Nakama no Kizuna), Shingo Yuuki (Kaze no Stigma).
Butter is voiced in Japanese by Tamotsu Nishiwaki.