Cell Phone Investigator 7: Pilot (2008)

Masaka Kubota plays high-school student Keita, who leads a secret life as a "network investigator" for a secret organization. In the introductory episode, Keita has moved to a new school in Tokyo but doesn't like it. His best friend from his previous school comes to Tokyo and they run away together. Passing through a construction site the pair are attacked by a robot, but are then saved by a man named Takimoto and his strange sidekick — a cell phone with arms and legs. This Buddy Keitai cell phone with "human intelligence capabilities" will go on sale in Japan in April.

Unfortunately the movie Cell Phone Investigator 7: Pilot is not yet available on HBO Max.