Naoya Kaido

Naoya Kaido (海堂 直也), also known as the Snake Orphnoch (スネークオルフェノク) is the third member of Kiba's trio in Kamen Rider 555. He is also one of the Renegades. He briefly used the Riotrooper belt.

Personality
He is a young man with an overly eccentric personality prone to incredibly fast speeches and constant mood swings. Kaido is often inconsiderate and selfish, but he's always been straight-up and honest about his feelings with people in his life. His greatest past-time is to play his guitar, but due to his hand injury, it often reminds him of the regrets he had as a human.

TV Series
He played the guitar in his younger days, but sabotage from his teacher destroyed some of the motor-skills in his left hand, forcing him to abandon his music. He is later made a 'sired' Orphnoch by Eiichi Toda as an example to Kiba and Yuka of how Orphnoch must make allies, using a snap of his finger to trigger his transformation into Snake Orphnoch (スネークオルフェノク). Learning of the changes after his enhanced ability to smell cost him a part-time job and being targeted by a corrupt employer, Kaido decides to abuse his power for personal gain when he encountered Faiz, with Kiba coming to his aid.

He greatly mistreats Yuka accidentally due to her crush on him. Continuing to struggle with his nature as an Orphnoch, Kaido ends up living with Kiba and Yuka, although he is the least concerned about protecting humans. At times he sides with Smart Brain over Kiba and Yuka, but his powerful and soft-hearted conscience often stops him from committing heinous acts at the last second. He eventually develops a partnership with Keitaro, which results in many harebrained schemes to win the respected woman of their desire, and bonded with Teruo. He briefly wore one of the six Riotrooper gears under Kiba's term in Smart Brain, the two switched roles, with Kaido throwing away his Riotrooper belt at Kiba out of disgust for his friend's new attitude.

Kaido would later save and befriend an orphaned boy, Teruo Suzuki, from a fire. Little did he know it's the future Orphnoch King. Eventually, Kaido's and his friends eventually figured out that Terou is the messiah the Orphnochs has been waiting for and the Kamen Riders face them in a final epic battle. Unfortunately, both Naoya (as Snake Orphnoch) and Mihara (as Delta) are powerless to stop the Arc Orphnoch as it took Faiz and all of the riders to stop him. After the final battle, Naoya watches the orphanage (now run by Mihara and Rina) before he departs for an unknown destination.

Paradise Lost
In the movie, Kaido, Yuka, and Kiba were on humanity's side. However, the humans didn't trust the Orphnnochs and demanded proof of their loyalty by sabotaging Smart Brain. Unfortunately, it was a trap by Smart Brain and the trio was brutally defeated by Smart Brain's most powerful creation, the Elasmotherium Orphnoch. Yuka was mortally wounded and Kaido tended to her as she faded away. It was in their final moments that Kaido confessed his love for Yuka. Not long after Yuka expired, Kaido ran a suicide attack and was eaten alive by the Elasmotherium Orphnoch. Kiba, being the only survivor was recovered, but also tricked into thinking that it was the humans that deceived them and vowed revenge for his friends.

D-Video Special: Kamen Rider 4
Before the last time looping after Shinnosuke died to prevent Go's fate from being killed in the first episode, Kaido was seen watching Drive's dead body while also watching Faiz and Zeronos battle three Shocker's remnants.

He helped Yuto and Shinnosuke by revealing that it has everything to do with Takumi. He temporarily works for Shocker to make Takumi realize what he has done with the kind of desire he had. He died in a modified timeline, but revived once Takumi sacrificed his life to destroy the timeline modifier. Once the timeline restored with most people has no recollection of Takumi existing, Kaido is the only one who remembers him, implying that he is still alive somewhere.

Kamen Rider 555 video game
The Snake Orphnoch is one of several Orphnoch who are playable in the Kamen Rider 555 video game.

Faiz

 * SB-555B Faiz Driver - Faiz's transformation belt.
 * SB-555P Faiz Phone - The control unit of the Faiz Gear.
 * Faiz Mission Memory - A small metallic card key containing the information of the Faiz Armor.
 * SB-555C Faiz Shot - Digital camera-shaped knuckle-duster.
 * SB-555L Faiz Pointer - A laser pointer which enables to produce an energy drill deathblow.

Riotrooper

 * Smart Buckle - Riotrooper's transformation belt.
 * Axel Ray Gun - A gun with a similar design to Faiz's SB-555H Faiz Edge and SB-555P Faiz Phone.
 * SB-RTV Gyro Attacker - A motorcycle with the same design to SB-555V Auto Vajin.

Portrayal
Naoya Kaido is portrayed by Mitsuru Karahashi (唐橋 充) who later played in  and later Miyamoto Musashi in Kamen Rider Ghost. As the Snake Orphnoch, his suit actors were Hideki Hato (葉都 英樹) and Keizo Yabe (矢部 敬三).