Kosuke Nitoh

Kosuke Nitoh (仁藤 攻介) is the secondary rider of Kamen Rider Wizard, Kamen Rider Beast (仮面ライダービースト). He make his first appearance in the 2012 Movie War film, Kamen Rider × Kamen Rider Wizard & Fourze: Movie War Ultimatum. Referred to as "the ancient magician" (古の魔法使い, Inishie no Mahōtsukai) by the Wiseman due to his ancient Belt, he needs to absorb the mana of the defeated Phantoms in order to regain his strength.

Kosuke Nitoh
Kosuke Nitoh is a student archaeologist who is rather optimistic, believing staunchly that dangers & opportunities are two sides of the same coin.

As a child, Kosuke was always scolded by his grandmother for being too adventurous. Ever since he found a fossil near a lake, he dreamed of becoming an archaeologist. Though his parents approved his ambition, his grandmother did not, resulting with Kosuke angrily viewing her as permanently angry with him.

During one of his expeditions, Kousuke accidentally discovered the Beast Driver in ancient ruins. He also has an unusual liking for mayonnaise, constantly carrying a bottle of it with him and putting it on any food he eats, including doughnuts and oden. Haruto and Shunpei refer to him as "Mayonnaise" because of this unique habit. When he finds Phantoms or Ghouls, he refers them as his "food" due to his ability and need to absorb Mana from them. It's shown that when Haruto finds Phantoms and tries to defeat them, Kosuke will get angry for interfering with his "feeding time". He also constantly leaves everyone around him speechless due to his tendency to interrupt others and express his thoughts without breaks.

While he originally saw Haruto as a nuisance, he was nevertheless willing to cure him of the poison injected into him by Manticore through the use of Dolphin Mantle's powers. After the incident with Oikawa, he gradually warms up to Haruto and sees him as a rival as well as a friend. Initially homeless and having to camp in places until he got chased away, he found a permanent spot to set up his camp at the roof of a building belonging to a woman whom he had once saved. Though, he still prefer to camp in many places.

Later, Kosuke revealed to Haruto, Shunpei, and Rinko that he received Kamen Rider Beast's powers from Beast Chimera. The Beast Chimera make a contract with Kosuke, granting Kosuke his magic. In exchange, Kosuke must absorb mana by defeating Phantoms and ghouls, or he will be eaten by Beast Chimera. Unlike Haruto who is knowledgeable about how Phantoms come about and operate, Kosuke initially knows nothing other than they can take human forms and he needs to eat them to survive. Later, Haruto offers Kosuke to get rid off Beast Chimera. However, Kosuke refuses and prefers to retain his powers and the status of being both a rival and an ally to Haruto. Even when he lost his Beast Driver. Kosuke refuses to destroy Chimera, since becoming a hero is his hope.

Rise of Beast
Kosuke meets Haruto, Shunpei, and Rinko by chance during a Ghoul attack, when he was about to have his lunch. Kosuke is then mistaken as a Gate by Haruto. He decides to keep eye on him, much to Kosuke's chagrin, who sees Haruto's intervention to have "ruined his meal". However, the Phantom Manticore was also sent by Wiseman to attack Kosuke. Haruto transforms during the attack into Wizard to guard Kosuke, while Shunpei and Rinko takes Kosuke away from the scene.

Meanwhile, Kosuke, annoyed by the trio's attempt to keep him safe, ran off on his own and met a tarot fortune teller, whom he had taken an interest in. Kosuke then decide to let the fortune teller predict his future. The fortune teller tells Kosuke that his future is bleak, but Kosuke, due to his super positive mindset, retorts in a cheerful manner that wherever there is a danger, there is an opportunity waiting. He further irks the fortune teller by saying that even hope can be found within despair. The fortune teller is later revealed to be Manticore when Haruto arrives to save Kosuke, and chokes Kosuke as Manticore revealed himself.

Instead of feeling afraid like victims usually do, Kosuke is overjoyed instead. Due to Haruto's inability to fend off Manticore in his current state, and that Kosuke desperately "needs to feed", he transforms into Kamen Rider Beast. After making short work of the Ghouls (and devouring their magical energy), Kamen Rider Beast takes on Manticore and uses Chameleo Mant to attack the Phantom unseen and gives him a hard time.

When Haruto tries to warn Kosuke of Manticore's poison attack, Kosuke was caught off-guard and the Phantom successfully poisons Kamen Rider Beast. However, Beast uses Dolphi Mant shortly afterwards to cure himself and Haruto, further angering Manticore. Kamen Rider Beast then uses Falco Mant and overpowers Manticore, and finally finishing the Phantom off with Falco Saber Strike and absorbing his Mana.

Though greeted by Haruto over his victory, Kosuke says nothing to reveal his origins as Kamen Rider Beast, but warns Haruto in a peculiar manner to never again interrupt his "meal".

Magical Food
Kosuke was seen having his camp set up and enjoying a barbeque in a shrine, but was asked to leave by a temple elder. He then sees an artist, Hiroshi Oikawa, being attacked by the Hydra Phantom. Haruto also arrives at the scene and immediately transforms into Kamen Rider Wizard to engage the Phantom. Since he was the first to spot the phantom, Kosuke is annoyed by Haruto's interference yet again, and he tranforms into Kamen Rider Beast to proceed to fight Hydra Phantom as well. Upon realisation that he has to fight two magicians at once, the Hydra Phantom decided that his chance of coming on top is too slim and escapes in the midst of Wizard and Beast's bickering over who should fight the Phantom. Kosuke then accused Haruto, saying that it was his fault that his "meal" escaped again.

Taking a break at the donut shop, Haruto is curious about how Kosuke obtained Beast's powers. Kosuke then tells Haruto and friends about the story regarding him and Kamen Rider Beast. Apparently some time ago, Kosuke was an archeologist who went on expedition discovering some ancient ruins. Soon, he chanced upon the Beast Driver and met the Beast Chimera, who then forced a pact on the then dumb-founded Kosuke. To his utter surprise, several Ghouls were released within the cavern's vicinity, but he managed to transform for the very first time and defeat them as Kamen Rider Beast.

Some time later, Haruto is alerted that the Hydra Phantom is going to attack Hiroshi once again. On the other hand, while sending Griffin to look for the Phantom, Kosuke meets Misa, who is actually trying to make use of him by lying that Haruto is trying to destroy the Hydra Phantom so that he can absorb the phantom's mana, as well as telling him that Gates have Phantoms ready to be harvested in them, though expectedly leaving out the additional detail of require the Gate in question to fall into despair and die first. Acting on impulse and choosing to believe Medusa despite her being a Phantom, Kosuke rushed to the scene of battle quickly to stop Wizard. While Wizard in his Water Dragon form is engaging the Hydra Phantom, Kosuke then transforms into Kamen Rider Beast with Buffalo Mant in an attempt to stop the battle. In the midst of the skirmish, Kosuke wants to know which side, Wizard or Phantom, can offer him a better deal in providing him the mana of Phantoms.

Today's Life, the Life of Tomorrow
After battling Wizard Water Dragon, Kamen Rider Beast decides to retreat, but he kidnaps Hiroshi also. Kosuke then asks Oikawa how to unleash his inner Phantom. However, Oikawa leaves as he had no idea what Kosuke is referring to. In spite of that, Kosuke still accompanies Oikawa to his home. At Oikawa's home, Kosuke found out that the source of Oikawa's hope is his portrait of his late wife. Since his wife had passed away, Oikawa had stopped drawing due to the lack of encouragement. A moment later, Haruto, Rinko and Shunpei reached Oikawa's home. Kosuke then meets Haruto, who told him that Gates are not merely Phantom lures. Instead, they are humans with magical potential, and can be turned into Phantom if they fall into despair. Kosuke was dumbfounded by this, as he must keep eating Phantoms that conflicted with what Gates are. However, sacrificing a human to become the Phantoms will leave a bad aftertaste.

Later, Rinko and Shunpei proceeds to move Oikawa's wife picture to a safer location for fear that a Phantom may destroy his source of hope. On their way, they encountered Hydra Phantom and Ghouls. Rinko and Shunpei are helpless against the numerous Ghouls, as one of them took the opportunity to grab the picture. Hydra Phantom then destroys it in order to let Oikawa fall into despair. However, Kosuke arrives in fashion with a flying kick on one of the Ghouls. Kosuke then transforms into Kamen Rider Beast, and Haruto arrives and also changes to Wizard. The two then use Buffa Mantle and Land Style respectively to defeat the Ghouls. Wizard then decides to let Beast to take care the Underworld Phantom, while he battle Hydra Phantom. While Wizard Land Dragon defeats the Hydra Phantom, Beast encounters Bandersnatch Phantom in Oikawa's underworld. Kamen Rider Beast tried his best to defeat the Underworld Phantom, but then it became apparent that he is not so strong enough to do it alone. Hence, Beast summoned Beast Chimera, which overpowered the Bandersnatch Phantom without much effort. Beast Chimera then defeat the Underworld Phantom using its finishing attack.

Kosuke then meet Haruto, who thanked him for helping to defeat the Underworld Phantom. Haruto then offers Kosuke to get rid of his inner Phantom, the Beast Chimera. However, Kosuke refuses the Engage Ring at last second for two reasons. First, it is very awkward if a man takes a ring from another man. Second, Beast Chimera is very strong, it will leaves a bad aftertaste if Haruto dies battling his inner Phantom. In addition, Kosuke prefers staying as Haruto's eternal rival. However, the question is how long will Kosuke live.

Beelzebub Plans & Dragons' Wild Dance
On a windy night, Kosuke still doesn't eat any Phantoms and swear to Haruto that he will find the Phantom first. When Wizard fights Beelzebub, Kosuke joins the fray for eating some Ghouls. Kosuke then changes into Beast and use Chameleo Mantle to defeat all Ghouls. He then uses Buffa Mantle to easily handle the Ghouls. However, when Wizard Flame Dragon attempted to attack Beelzebub, it redirected through a portal to Beast. The attacks kept injuring Beast much to the Rider's annoyance. After Wizard Flame Dragon is defeated, The White Wizard easily dispatches Beelzebub. White Wizard then states that Beast is an archetype Wizard. The White Wizard  then disappears, before Beast could ask any questions. Rinko arrives to inform Kosuke and co. that Beelzebub can control people with his slugs. Kosuke and Shunpei rush to destroy the slugs. However, destroying the slugs proves useless as Beelzebub can control people directly. Kosuke then battles Beelzebub as Beast again, but is easily overpowered. However, Haruto arrives with Drago Timer to summon the Dragon Styles clones. Beelzebub is then defeated by the combined power of the Wizard Dragon Styles.

On Phoenix's Rampage
Kosuke is having trouble finding the Phantom since Haruto always finding it first. So he decided to ask Haruto to see if he find any Phantom lately. As Haruto is going to the location where Phoenix is, Kosuke follows him. Kosuke as Beast arrive in the to distract Phoenix as Wizard takes Rinko to the Hospital. Just as Beast finish Phoenix off, the attack wasn't strong enough and Phoneix defeated Beast. After Kosuke is defeated by Phoenix, he got injured and went to Antique Shop Omokagedo. While Haruto is in the hospital, Kosuke arrive and fought Phoenix before he tell Beast that he wants to fight Wizard on the location where they first fought. After that, he tell the gang about Phoenix's message and wanted them not to tell Haruto. However, Haruto got the message thanks to Koyomi, so he decide to let Haruto to settle things off from Phoenix.

Reunion with his Grandmother and the Choosing of the Lives
When his grandmother, Toshie visits Tokyo, she came there to pick her grandson back home. As Kosuke is surprise to see Toshie, he tells the gang not to tell her that he is a Wizard because he thinks that he will get scolded. As he ran away from Toshie, Shunpei take her a tour in Tokyo until they were attack by the Weretiger Phantom. Shunpei calls Haruto that Toshie is a Gate which Kosuke is surprise to hear. As the Phantom is about to attack her, Haruto and Kosuke arrive in time and fight the Phantom. Before fighting the Phantom, Kosuke hide somewhere to transform while Haruto as Wizard fought Weretiger. After Kosuke transform, he started to act different so Toshie won't notice him. As the Phantom escape, the gang went back to Antique Shop Omokagedo as the fight continues between Toshie and Kosuke. Kosuke leave the store angrily as Haruto ask him why does he hate Toshie. While Haruto takes to Kosuke, Toshie thinks that she might be too forceful to her grandson and knows that Kosuke doesn't care for her, but Shunpei thinks that her grandson have some feeling for her. On the next day, Haruto and Shunpei takes Toshi back to Fukui Prefecture, while Kosuke, in disguise seeing her grandmother going back home. As they enter the bus, the door closes on Haruto and drove away. Haruto chase the bus to wait until the driver reveal himself as the Phantom. In the bus, Weretiger summon some Ghouls to attack the Gate. However, Kosuke attack the Ghouls before revealing himself to Toshie that he is Beast. After fighting some Ghouls in the bus, Wizard arrive using the Big Ring to stop the bus. As the bus stop, the Phantom got out and attack the Wizards, which they accidentally swap rings. While the Wizards fighting the Phantom, Toshie tell the Phantom to put her into despair which got the Wizards confuse. Before the Phantom put Toshie in Despair, Shunpei protected her, but he got injured badly. As the Wizards are going to rescue Shunpei, Gremlin appeared and make a bet to them so they use Shunpei as a hostage, if they bring Toshie to the Phantoms. After that, they went back to the store, and worried which one to save. Toshie then explain her reasoning why she wants to be a Phantom is to feed Kosuke. However he thinks that it is stupid, so he ran out of the store. As he went outside, he started to see why Toshie is too forceful on him: she wants her grandson to be safe. Kosuke went back to the store and tell his grandmother not to sacrifice herself because it will make him fall into despair. After the talk, they started to plan to save Shunpei and Toshie. On the next day, when Kosuke gave his grandmother along with the Beast Driver to Gremlin, Weretiger attack Kosuke so Toshie can fall in despair. Just as Weretiger deliver the final blow, Kosuke scattered into feathers. While that happens, Haruto attack the Phantom saving Shunpei and retrieving the Beast Driver. After that, they reveal their plan the Phantoms before fighting them. After the fight, Kosuke take Toshie back to Fukui Prefecture.

Identifying Medusa and the Bond of Sisters
Before Kosuke can eat his breakfast, the girl approach him and walked over from him. As he saw her face, he thinks that she was the Phantom that they met before. So Kosuke chase after her, before he saw people are running away from the Phantom. As he arrive, Medusa is about to put the Gate in despair, but he interfere and fights her. After the fight, Medusa flee off and Kosuke found her human form, but he got arrested for harassing a student. In the Toriizaka Police Station, Kosuke beg Rinko to believe him that the high school girl is a Phantom. So Rinko do her research, until she find out that Mayu has a twin sister, Misa. As Rinko freed Kosuke, he arrive where Wizard and Medusa are fighting and fight off some Ghouls.

As Medusa manage to escape, Kousuke, Rinko, and Shunpei take the Gate to the police station for her safety. On the next day, the Ghouls started to attack where the Gate is and Kosuke fought the Ghouls. As they were running from the Ghouls, Gremlin appeared and fight Beast, until Wizard arrives. While they are fighting, Gremlin reveal to the magicians that Mayu is also a Gate and she is with Medusa. After that, Wizard in Hurricane Dragon flees off along with Rinko to Mayu's old house, while Beast fight Gremlin, before he takes off.

The Stolen Belt and Beast Hyper
Kosuke read an article about an archeologist named Osamu Nakamoto, who recently found two new items for Beast. When Kosuke finds Osamu, he asks him to see the ring and the stone that he found, but Osamu leaves. As he is exiting out the parking lot, the Spriggan Phantom attack him, who turns out to be a Gate. Kosuke arrives just in time to fight the Phantom.

While they are fighting, Osamu notices the ring has a lion on, which is similar to Beast. After the fight, Osamu asks Kosuke to come with him. When they arrive in Osamu's room, he does some research on Beast. After that, Osamu and Kosuke celebrate, until Kosuke passes out drunk. The day after Kosuke hears Osamu scream as the Phantom attack. Before he transforms, Kosuke is shocked that his belt and ring were missing. Gremlin appears and Kosuke wants him to return his things. However, Gremlin doesn't know what he is talking about and challenges Kosuke to a fight. As the fight continues outside the building, Wizard appeared fighting Spriggan.

When Kosuke is seriously injured by Gremlin and Osamu is being attack by Ghouls, Wizard use the Drago Timer to summon his clones. As the Phantoms escaped, Haruto, Kosuke, and Osamu went back to Antique Shop Omokagedō, as Haruto decide to give some of his mana to Kosuke, but it doesn't work. After that, they went to Osamu's room and question him about how the Phantom entered his room and stole Beast's equipment. After Osamu answesr their question, Haruto and Rinko think that he took the belt and rings from Kosuke. Kosuke ask Osamu if he took his belt and ring while he was sleeping.

This upset Osamu and he go out. Haruto then comes up with a plan to make a fake Beast Driver and trick Osamu into thinking that they found it. As they succeed, Osamu reveals that he doesn't want others taking his credit. As Spriggan enters the room, Haruto keeps him distracted as Kosuke get his stuff back. Before he leaves, Osamu gives him new items and realizes his dream. Kosuke arrives where Wizard and Spriggan are fighting and transform into Beast and fights some Ghouls. Realizing that his body got weaker, he use the Hyper Ring and change into Beast Hyper. With his new form, he overpowers the Phantom and finishes off with a Magnum Strike. After the fight, Osamu leaves Japan to discover new things.

The Day Magic Vanished and Tears
Kousuke saw Legion attack a human, so he transform and fights him. After the fight, Beast ask him why he attack a Gate, until Legion respond that he had no interest of the Gate, instead he only thinks what's beautiful. Sometimes later, Rinko and Haruto arrive as Kosuke tells them that Legion is the one that made the victims went into a coma and he will be attacking random people when they do something beautiful. Kosuke as Beast arrive where Wizard and Legion are as he joins the fry. However, Legion was shown to be too powerful for the magicians as he slash through Wizard, which opens a portal to Haruto's Underworld. Legion enters the Underworld as Beast follows him so he can stop him from destroying Haruto's Underworld. As Legion is about to finish Beast off, WizarDragon blocks the attack which destroys him and meaning that Haruto can no longer use magic as his inner Phantom was destroyed.

Beast was ejected out after WizarDragon was destroyed along with Legion. Kosuke and Shinpei take Haruto back to the shop as he tell the gang what happen to him. While searching for Legion, he found Haruto and tells him to let him fight Legion alone and also saying that only magician can defeat Phantoms. As he find Legion, he fights him, but he trapped Beast, so he can continue to search for Haruto in order to destroy his mind. As Rinko and Shunpei manage to free Kosuke from the trap, they arrive where Haruto was and witness his magic returning and accessing into Infinity Style.

The Dangerous Part-Time and Money Shouldn't Buy
Kosuke was surprise to see his high school friend, Masataka Tsuchiya living in Tokyo in a run down shack. Masataka tell him that a job offer that promises to pay ¥1 million for each day of work and Kosuke joins him on the interview. At the job interview, Masataka and two other canidates tells a gloomy man all dressed in black why they want to take the job. Sometimes later, Masataka got accepted while Kosuke didn't make it. Kosuke visit the shop and tell the gang about the job that his friend is taking. They decide to see what job it is until Haruto notice that recognizes one of them among he saved from the Ghouls the other day. So Haruto and Kosuke sneak into the building with their Magic Rings. As they enter the building, they couldn't find any Gates, until they confront Medusa. She tells them the plan and where the Gates are going. As they arrive in Yokohama where the Gates are, they see that the gloomy man is the Bogy Phantom. They transform and fought Bogy while getting the Gates to safety. After Bogy was destroyed, he tells Masataka to get away from Tokyo as he gave Kosuke a charm that represent their friendship.

Sometimes later, Kosuke was surprise that Masataka didn't leave Tokyo. He tell Kosuke that he will leave Tokyo, however his luck rises which stops Masataka from leaving the city. Kosuke got a call from Haruto which he tells him that Bogy is the one that can control luck for the Gate. After the call, he tell Masataka that the Phantom was controlling his luck, however he didn't believe him and thinking that Kosuke was jealous of his luck. As he trying to stop him, Masataka pay some thugs to beat him up and tells Kosuke that they are no longer friends. Knowing that his friend have change, he arrive where Masataka is and save him before the car explodes. As Masataka finally comes to his senses, he ask Kosuke to destroy Bogy. After Bogy was destroyed, Masataka vows to never forget about their friendship again.

Super Hero Taisen Z
Beast is set to appear in Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, where he fights Space Sheriff Sharivan. He is also teamed up with Kyoryu Gold.

Super Hero Taisen Otsu
to be added

Protecting the Model
to be added

Kamen Rider Battride Wars
Kamen Rider Beast appears as a Second Rider in the video game Kamen Rider Battride Wars.

Mantles
Unlike Wizard, Beast doesn't use alternate forms to combat the Phantoms he consumes. Instead, he uses single shoulder mantle armaments called Mantles (マント, Manto) to help him gain an advantage over his foes.

Kamen Rider Beast's ending theme is entitled "BEASTBITE".

Devices

 * Beast Driver - Transformation device
 * Dice Saber - Kamen Rider Beast's weapon.
 * Beast Colors - Gives access to Beast's mantle changes.
 * Griffin PlaMonster - Kamen Rider Beast's familiar.
 * Mirage Magnum - Kamen Rider Beast Hyper's weapon.

Quotes

 * "Now, it's lunchtime!" - pre-battle catchphrase.
 * "The main dish!" - Beast's catchphrase, before executing a finisher.
 * "Now it's breakfast time" - pre-battle catchphrase said in the mornings when he has not eaten yet.
 * "A pinch is a chance" - a catchphase usually said when he finds himself in difficulties.

Portrayal
Kosuke Nitoh is portrayed by Tasuku Nagase (永瀬 匡). As a child, Kosuke is portrayed by Kirato Wakayama (若山 耀人).

As Kamen Rider Beast, his suit actor is Jun Watanabe (渡辺 淳), which the role he reprises first in Movie War Ultimatum. This is his first secondary rider role. He is also Phoenix's suit actor.