Raito Sonozaki, or by his adopted name, Philip is the right sided-half of Kamen Rider W or Kamen Rider Double. Being an avatar to the true Gaia Memory of the planet Earth itself, 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 Shoutarou, projecting his mind into Shoutarou's body to form the right half of Kamen Rider Double. Philip represents the mind of Double.

(Source: Kamen Rider Wiki)