Ryujiro Mizunuma is a character appearing in the Yu-Gi-Oh! VRAINS anime. He calls himself Mad Marsh.
Ryujiro uses a "Zombie" Deck. His strategy is to summon multiple Zombies with 1000 or less ATK so that he can use them for defense and getting card advantage, then use Edge of Darkness to easily search out and summon "Despair from the Dark".