First Appearance: Episode 28
Naoto and Tatsuya (TimeRed) met at an Interscholastic Athletic Meet, where Naoto defeated Tatsuya in the final competition to become Number One, with Tatsuya coming in as Number Two. With the scholarship prize, Naoto ended up at the same school as Tatsuya. While Tatsuya tried to make friends with him, Naoto rejected it, as he was a poor kid looked down upon by the rich snobs who went to the school and believed Tatsuya was the same. After awhile he grew sick of it all and left, carrying several resentments and a feeling of powerlessness he was determined to change.
When next the two meet, Naoto has already joined the City Guardians, an elite force created by Tatsuya's father to protect the city from the mutants (for a price, of course). Recognizing TimeRed's voice to be that of Tatsuya's, Naoto's supposition is proven later when TimeRed's helmet was broken, revealing Tatsuya to be underneath. When the Guardians arrive to protect the dig site from the mutant (along with the Rangers), Naoto happens to hear what they are fighting over and takes off with it. He will eventually use the Control Box to get the V-Commander and turn into TimeFire. Wanting to move up in the ranks, when he overhears Takku (Circuit in NA) telling the other rangers about the V-Rex, he vows to gain control of it first and return to the Guardians with so much power, they cannot ignore him. As such he is promoted to become leader of the City Guardians, directly under Wataru Asami (Tatsuya's father).
It takes a while for Naoto to learn that the mutants attacking the city are escaped prisoners to be recaptured, not simply destroyed. It is Sion (TimeGreen) who eventually gets through to him, when trying to protect a friendly mutant. As time goes on, Naoto starts becoming closer to the other Rangers, and even felt empathy when he overheard Tatsuya tell the others Ayase (TimeBlue) was dying.
When Asami is hospitalized, Naoto uses the opportunity to gain take full control of the Guardians.
Naoto had two pet birds, Sakura and Tora, which he gave to a little girl when he moved out of his apartment.
After being injured in the battle against NeoCrisis, Naoto learns Asami has re-taken control of the Guardians through a legal maneuver. Kicked out of the Guardians, Naoto quickly flees before they can take the V-Commander from him, revealing they can remove the voice-lock, which prevented anyone but him from using it and controlling the V-Rex. He continued to fight alongside the TimeRangers, but in the finale was shot (in the same spot as his previous injury) by a Zenitt (Cyclobot in NA) and fell from the top of a high-story building. With his dying breath, he passed the V-Commander into Tatsuya.