TV-Series
Description
Daichi Ōnishi, referenced as Kenneth Onishi in English-language materials, is a human archaeologist renowned as the world's foremost expert in energy applications. He has a wife rarely mentioned and is father to Koji Onishi. Ōnishi led a significant excavation beneath Metro City targeting ancient ruins emitting powerful energy signals, though progress stalled against an impenetrable energy shield. His expertise later took him to an International Scientific Symposium in New York, where Megatron abducted him after the Predacon leader incapacitated attendees with a Sonic Pain Wave.

During captivity, Predacons employed a psycho-probe to extract Ōnishi's knowledge. This revealed key locations: the Payuma ruins (explored with Koji), the Cave of the Dragon (mistaken by Predacons for a robot lair), Montrose Island (site of a second O-Part), and a crashed Cybertronian spaceship in America. The probe also surfaced personal memories, including his enthusiasm for vintage trains. Predacons misinterpreted footage of a steam train, intended for Koji, as a superweapon schematic. These memories provided Ōnishi hope during imprisonment. A critical microchip, hidden in a picture frame at his home, was later found by Koji and Side Burn. Its data proved vital for Autobot missions to locate O-Parts and the spaceship.

Following his release by Sky-Byte (aiming to outmaneuver rival Predacons), Ōnishi reunited with Koji. He then partnered closely with the Autobots' AI, T-AI, to decode the microchip data and O-Parts. This collaboration led to the discovery of the Orb of Sigma, Cerebros, and Fortress Maximus. Ōnishi assisted in developing control protocols for Fortress Maximus, including a breakthrough where Koji's commands stabilized the giant robot during its Metro City rampage. Later, as Scourge attempted to control Maximus in the desert, Ōnishi coordinated the deployment of Team Bullet Train and the Build Team carrying human children; their collective bio-signatures successfully overrode Scourge's control. He expressed pride in Koji's bravery despite the risks.

Beyond the primary conflict, Ōnishi contributed to the Spark Engine's development alongside Dr. Haruma Gō, upgrading Spy Changers into Super Spy Changers to counter Mutants from Cybertron. He also participated in the Raiden Initiative, designing power systems for the Trainbots and naming the DE10 diesel locomotive "Kaen" (symbolizing a flame in service of Japan and humanity). In a separate continuity, he collaborated with scientists Brian Jones, Felix Adle, and Peter Morris to achieve commercially viable solar fusion.

A version of Daichi Ōnishi from the Legends World appeared outside the Tokyo Toy Show, observing a multiversal Sky-Byte. He was later included in a group shot of Autobot-allied families during the Transformers 40th Anniversary Special. His English first name, "Kenneth," originated from Fox Kids' episode summaries and was not used in the original animated series.