And it’s another prominent one who’s been in many other anime.

関 智一 Seki, Tomokazu has stated he’ll be appearing in Yu-Gi-Oh! VRAINS in an upcoming episode as the character(s) カエル and 鳩. Kaeru (Frog/Tod) and Hato (Pigeon/Dove).

Who these characters are are unknown.

But what is noteworthy is Seki Tomokazu is one of the bigger names in the industry, known for roles such as:

Gilgamesh for the Fate franchise

Domon Kasshu of G Gundam

Suzuhara, Toji of Neon Genesis Evangelion

Haru Glory of Rave Master

The modern voice of Honekawa Sueno of Doraemon

Tatsumi, Kanji of the Persona franchise

i.e. If you’ve watched a major anime, you’ve heard this guy in some way shape or form, at the end of the day.

Source