TV-Series
Description
Koji Onishi (Japanese name: Yuki Onishi, 大西勇気) experiences a life-altering event when Predacons abduct his scientist father during a New York symposium. This leads him to meet Optimus Prime in Metro Park, where the Autobot leader reveals his Cybertronian origin. Optimus transports Koji to New York via the Global Space Bridge, though they arrive too late to prevent the abduction.

Koji subsequently becomes a regular presence at the Autobots' underground base, serving as their cultural ambassador to interpret human society. He forms a bond with the sentient AI T-AI, initially believing her hologram to be physical. His strategic insights aid multiple missions: proposing stratospheric disposal of an explosive over Metro City, relaying communications during a bullet train rescue, and alerting Autobots to Predacon activities at sites like the Cave of the Dragon and Sherman Dam. Knowledge from childhood trips helps navigate locations such as the Payuma ruins and Black Pyramid, where he discovers a hidden microchip in a family photo, bolstering the Autobot cause.

His father's captivity remains a constant concern. Koji distracts himself by cycling with friend Carl and visiting power plants or baseball games, though Predacon attacks frequently disrupt these outings. His perception of the Predacon Sky-Byte shifts dramatically when Sky-Byte rescues Dr. Onishi, delivering him in a container. Koji then hails Sky-Byte as a hero, joining other children to seek the Predacon's autograph. Post-rescue, he aids in recovering O-Parts and insists on joining the Orb of Sigma mission to protect T-AI. During this operation, he retrieves the Orb from Megatron and returns it to base. Later, he halts the rampaging Fortress Maximus with a direct command.

Koji's mother appears briefly during the initial abduction but receives no further mention. He maintains friendships with Carl and Jenny, witnessing Sky-Byte defend the CGA Tower alongside them. Skeptical of Ultra Magnus's initial hostility, Koji later inquires about the Autobot's connection to the Matrix of Leadership.