Created by Steven T. Seagle and Duncan Rouleau in their spare time while working on another project, Hiro was first intended to appear with the rest of Big Hero 6 in Alpha Flight #17 (December 1998).

However, the team first appeared in their own self-titled three-issue miniseries by writer Scott Lobdell and artist Gus Vasquez, which due to scheduling issues, was published before Alpha Flight #17.

Silver Samurai, Big Hero 6's initial field leader, first approached Hiro's mother for permission to have him join the team, but she refused as she wanted her child to live a normal life.

However, after his mother was abducted by the Everwraith, the astral embodiment of all those killed in the 1945 nuclear attacks on Hiroshima and Nagasaki, Hiro was forced to turn to Big Hero 6 for assistance.

Although he is only an adolescent, he is a visionary theoretician and accomplished machinesmith who has already made several breakthroughs in fields such as robotics, computer science, synthetic polymers, geology, biology, and communications.

Hiro has constructed several robots, his first and most advanced creation being Monster Baymax, a water-powered synthformer whose artificial intelligence is based on the thoughts and memories of his departed father.

Other notable inventions include: the Bio-Atomic Parcel Detector (B-APD), a device capable of pinpointing the location of human-sized nuclear reactors; a jet-pack-propelled flight suit that grants its user limited firepower capabilities; a holographic virtual reality projector that can produce a comprehensive recreation of previous events by amassing information from various data streams; and eyeglasses with a cybernetic video display that can connect to an assortment of computer networks.

[11] Speaking of the character, co-director Don Hall said "Hiro is transitioning from boy to man, it's a tough time for a kid and some teenagers develop that inevitable snarkiness and jaded attitude.

His older brother Tadashi, a student at the San Fransokyo Institute of Technology, inspires him to redirect his efforts toward gaining acceptance to its research program.