Ice Oni

Ice Oni is an artificial virus created by Queen, which he has weaponized with Excite Bullets. According to him, it is his best creation.

Description
Once a person is struck by an Excite Bullet with this virus, their skin will become covered in ice, causing them to feel extremely cold. They will grow a pair of horns in their head and their teeth will turn into sharp fangs, giving them the appearance of oni. This virus can quickly spread from person to person by simple physical contact, with one victim being shown biting an uninfected person with his sharp teeth to transmit it. The victims target anyone regardless of being ally or enemy.

Wano Country Arc
When fighting broke out on the Live Floor in Onigashima between the Ninja-Pirate-Mink-Samurai Alliance and the Beasts Pirates, Queen fired Excite Bullets from a Gatling gun at the enemy samurai, intending on closing off the room and spreading the virus to everyone in it.

Trivia

 * This virus is possibly inspired by the children's game "freeze tag," which is known in Japan as "Ice Oni" (こおり鬼).