Nitou Kousuke

仁藤攻介

First appearance in the series: Kamen Rider Wizard 17.

A series regular on Kamen Rider Wizard. He plays the second Rider.

Catch phrases

His main saying is "A pinch is a chance". Matching with his happy-go-lucky lifestyle, he sees desperate situations as opportunities.

He also has a habit of interrupting people and saying "Say no more!"

Personality

Seems to have a positive personality. His catchphrase seems to be "A pinch is a chance." He also appears to take eating/meals really seriously (Perhaps since his human form is a sort of drifter/bum character).

Apparently really likes mayonnaise since he carries a bottle of it around with him. Will even put it on doughnuts.

Because of his obsession with mayonnaise, Haruto and Shunpei nickname him "Mayonnaise".

Name breakdown

仁 - Virtue/humanity

藤 - Wisteria

攻 - Attack/Aggression

介 - Shellfish, mediate, concern with oneself

Kamen Rider Beast

仮面ライダービースト

Belt: Beast Driver. Activated with the Driver On Ring and Beast Ring.

Main weapon: Dice Saber

Theme song: Beastbite by Rider Chips.

Yells out "It's time to feed" at the start of battle.

Wiseman comments that he's an "ancient mage". When he defeats Ghuls and Phantoms, his belt can eat them to absorb their magical energies.

His various rings give him different mantles on the right side.

Origin

Was investigating some ruins after college. He stumbled upon a hidden cave. Inside it, he found a slab with the Beast Ring in the middle. The slab turned into a belt. Upon removal, rocks fell from the cave ceiling which turned into Ghuls.

That is when he hears Khimaira's voice. Khimaira explains that by using the belt, they have become one. As a consequence, Khimaira must be fed magical energy, otherwise he drains Kousuke's life energy until he dies.

Wiseman explains that Beast Belt was sealed by the Phantoms and is forbidden.

Kamen Rider Beast Chameleo Mantle

Activated with the Chameleo Ring カメレオリング on the right side of the Beast Driver.

Gives Beast the power to turn invisible.

Kamen Rider Beast Dolphi Mantle

Acitvated with the Dolphi Ring ドルフィリング on the right side of the Beast Driver.

Allows Beast to remove poison from himself and other people.

Kamen Rider Beast Falco Mantle

Activated with the Falco Ring ファルコリング on the right side of the Beast Driver.

Finisher:

Kamen Rider Beast Buffa Mantle

Activated with the Buffa Ring バッファリング on the right side of the Beast Driver. While the other animals just lose the last "n" in their name, Buffalo loses the whole "lo" part.

Khimaira

キマイラ

Voiced by Nishimura Tomomichi 西村知道

Appears to be a Phantom with the head of a lion, dolphin, falcon, buffalo, and the tail of a chameleon. He allows Kousuke to become the mage Beast, but must be constantly fed magical energy or Khimaira will feed upon Kousuke's life energy instead.

Trivia

Kousuke carries around a bottle of mayonnaise that has a label that is constantly changing. From "Itadakimasu" to "my personal bottle" to "put mayonnaise on it!"
Khimaira is the Greek pronunciation of Chimera. So it's fitting that in his introduction episode, Beast fights Phantom Manticore, a mythical monster also combined from several animals. Khimaira also has the different other beasts on his body. He has a Falcon and Dolphin head next to his Lion head and a Chameleon tail. There's also an Buffalo head on Khimaira's chest. The sub beasts all have their n dropped in their mantle form except buffalo which becomes buffa.
Since Khimaira bonds with Kousuke to turn him into a mage, that means we don't see what's inside Kousuke. But this could just mean that Kousuke doesn't have enough magical energy to form a Phantom inside.