S1, E6: One day, while Teruto is resting in his tent, an injured Naomitsu collapses in front of him. Sakura asks him what happened, and he explains that he just battled Dairo Keisen, also known as the “Card Professor,” who is a researcher of Witchcraft Medicine. Naomitsu fought Keisen because he heard rumors that Keisen was involved in dangerous human experiments and that someone powerful was supporting his shady activities. With each member having their own intentions, Teruto and his team embark on a journey to battle Keisen.