Through a misunderstanding as to how Kamen Rider Wizard functions, he labels Haruto his "eternal rival" when they first meet after Nito was targeted by Manticore on the assumption that he was a Gate. Despite it being possible for Haruto to simply use an Engage Ring to enter Nito's Underworld and destroy Beast Chimera, Nito initially refuses on the grounds that his Phantom would be too strong for Haruto to handle. Nito later explains that as an archeologist, he wishes to learn more about the Phantoms and the Wizard Rings, believing he will never make an important discovery again.
When Nito attempts to end the second Sabbath, he is overpowered by Fueki. In risky gambit that could have killed him, Nito broke the Beast Driver to release Beast Chimera so he can devour all of the excess magical energies generated by the Sabbath to negate the ritual. In appreciation, the idea of eating not amusing, Beast Chimera spares Nito's life and frees him from their pact before leaving. Despite being a normal human again, Nito aided Haruto during the final battle. Once the Phantoms are finally defeated, taking Yuzuru as an apprentice, Nito decides to find Beast Chimera to learn more about the ancient Phantom.
Kamen Rider Beast is also referred to as the "Ancient Wizard" and transforms via the Beast Driver. Akin to Wizard's Styles, Beast can change to different forms known as Mantles, which are named after the special cloak-like attachments that gives him powers of different animals. After Nito transforms into Kamen Rider Beast, he originally said "Now, its feeding time!" until adopting the phrase "Now, it's lunchtime to contrast with Haruto's own "it's showtime." Whenever Beast executes one of his finishers, he says "the Main Dish!".