Mystic monster: A-Kitus

Sero was a slug that has one and only dream: being one of the best scientists in the world. He was very intelligent, but due to his appearance, he can't do that. He's a creature part of Zoid's species, but disabled, as he looks like a pink slug. And because of that, he ignores this dreams and lives as a normal slug. But suddenly, a mysterious virus arrived in Gelida kingdom, capable of infecting and killing everyone. Sero is unable to get affected as this virus only kills people. However, there's no only one, but 2 types of virus, and yes, Sero has low chance to survive the 2nd one, as this virus has the same size as most of large insects, but it doesn't infect however. Sero fortunately survive that, and he enters into a small house and hides somewhere. But he was spotted by a monster that most of us know: Moonhaze and Karlo. Sero explains everything of what happened, and what he wants to do, and since Moonhaze is a kind monster, he helps Sero by giving him a stone of Mystical Opal, Sero immediately realize that he can creates a mystial robot with it that he's able to control him completely. And it worked! Thanks to Moonhaze, he's able to achieve his dream and found the cure against these 2 types of virus with his robot that has a new name: A-Kitus. But, who's the responsible of these virus?