Archfiend Tapir was an evil and powerful Tapir computer virus that infected Tama and tried to take over the world by spreading itself into all computers. He was the main antagonist of the Tama Quest Arc.
As a Tapir virus he was just a simple harmful software application, but after entering Tama and evolving due to her advanced software, he gained a humanoid yet monstrous form, with shaggy hair, horns, large bulky armor and a hideous appearance that was never fully seen. As he took over Tama's body, his appearance began to change and upon taking full control of her he began to look exactly like Tama in appearance and voice while still wearing the bulky armor.
Tama Quest Arc
Archfiend Tapir was originally a Tapir computer virus designed to evolve and become stronger than its host, which will ultimately destroy the host. It infected Tama while she was searching the internet, thus, he evolved into a highly advanced AI due to her advanced programming. With his new found intelligence and power, he became the most powerful virus in the world and sought a new ambition which was to take over all the computers in the world and become a true archfiend. He then produced countless Tapir subordinates to aid in his endeavor to take over Tama and then the world.