Philip

'Philip (フィリップ Firippu?) is the right sided-half of Kamen Rider Double. He is a mysterious young man who works as Shotaro Hidari's partner after he and Detective Narumi save him from an experiment conducted by the Sonozaki Family. Being an avatar to the true Gaia Memory, he has full access to the Gaia Library, which he often interfaces with to look up for information on Dopants, and has computational capabilities comparable to that of a supercomputer. He fights Dopants with Shotaro, projecting his mind into Shotaro's body to form the right half of Kamen Rider Double. Philip represents the mind of Double.

History
He is a mysterious young man who possesses the true Gaia Memory (地球の記憶 Chikyū no Kioku?). His real name is Raito Sonozaki (園咲 来人 Sonozaki Raito?), the third-born child and sole son of Ryubee, whose mind was altered by Satoshi Yamashiro under his father's wishes to have no memory of his name and family. It is also revealed to him that Raito actually died twelve years ago in a freak accident falling into a well connecting to the true Gaia Memory, but he was somehow revived as an avatar almost instantaneously. After being rescued by Shotaro and Sokichi Narumi from a mysterious organization, Philip helps investigate Dopant activity through his ability to access the Gaia Library (地球（ほし）の本棚 Hoshi no Hondana?), a collection of all of the information in the known world. However, due to having no memory of his life before being rescued and the need to keep his location secret from the people Shotaro rescued him from, he usually spends his time in the Detective Agency's secret hangar, reading about common topics that he finds interesting. He fights the Dopants with Shotaro as the mind and soul of Kamen Rider Double, providing the Gaia Memories for the right side of Double.

After being thrown into the Gaia Memory for the Gaia Impact and extracted from ClayDoll Xtreme, Philip's body became unstable to the point that should he transform into Kamen Rider Double, again, he would break up into data and completely be absorbed by the planet. Saving their final transformation to save Wakana and fight the Utopia Dopant, Jun Kazu, Philip has Shotaro promise to him that he will still fight for Fuuto even if he is gone. After Kazu is defeated, Philip bids his final farewell to Shotaro as he fades away once the transformation is ended. Before he left, Philip left Shotaro a gift containing a Lost Driver belt and the blank book he used to access the Gaia Library containing a message thanking Shotaro and asking him to continue to protect Fuuto. A few days later, after being rescued by Shotaro and Phillip, Wakana learns that Philip sacrificed his own physical existence to save her and initiates her own Gaia Impact to bring back the Xtreme Memory which slowly reconstructs Philip's physical body which took a year. After being revived, Philip has one last moment with his family who tell him that they will be watching over him. He then spent the next year, waiting for his body to restore and watched over Shotaro within the Xtreme Memory. Upon returning to physical form, he continues to protect the city of Fuuto as Kamen Rider Double.

Personality
At first, Philip was shown to be completely devoid of interest in human relationships, even calling himself 'a little devil'. Being extremely intelligent, he is mostly apathetic and shows interest only in common topics he finds interesting which he reads occasionally, sometimes even turning into an obsession that overwhelms him until he knows everything about that subject, often getting in the way of ongoing investigations. At times, he would even go to extremes where he would work himself out until he collapses, such as when he was reading on weight-loss, and getting himself very fat after getting obsessed with Mochi, a type of rice cake. After finding out everything there is to know about the topic at hand, he would completely lose interest in the said topic and move on to something else. Being apathetic and have little experience in interacting with people, he is seen to be a cold person who would often annoy people around him with cold hard facts presented in a completely tactless manner.

After spending time with Shotaro and Akiko, Philip's human and emotional side starts to surface and develop, and over time, he came to love Fuuto and the friends he and Shotaro made. While initially only saying it as a matter of fact, he eventually also comes to playfully tease Shotaro about being 'half-boiled', (which is by the way a truth most of the time) while still being his most trustworthy friend.

Philip maintained a close relationship with Wakana Sonozaki after helping her in the Violence Dopant case, which was further enhanced when he discovered his identity as Raito Sonozaki until Wakana was convinced to join in the Gaia Impact plan. He became devoted to bring his family out of their Gaia Memory plans so that they can be a true family again, even if it meant disappearing forever.

Abilities
Due to his status as the True Gaia Memory's avatar, his focus and intelligence are comparable to a super computer and he has access to the Gaia Library, which in turn means that he has access to any recorded knowledge on Earth. While this does not mean that he actually knows everything, his unparalleled ability to crunch enormous amounts of information in a very short time makes him looks as though he does know everything. While he is far more intelligent than Shotaro, his insensibilities and his status as a wanted person by the Museum means that he has to stay confined to the office and the hangar most of the time for his own safety. As such, he mostly helps Shotaro by looking for further information in the Gaia Library on any clues that his partner finds.

Being confined most of the time to the hangar doing researches, both before and after being rescued, he does not get to exercise much and as such, he is visibly physically weaker than Shotaro. The FangJoker transformation, which uses his body instead of Shotaro's, thus take a severe toll on him should he sustain the transformation for extensive periods. While he is technically capable of fighting, as seen when he is in FangJoker form, his weak body does not allow him to effectively do so outside of transformation. Despite being able to control the right side of any of Kamen Rider Double transformations, he usually yields full control to Shotaro when transformed while he acts as the battlefield tactician.