Kō Honda began his career as a professor at the Tokyo Institute of Technology and a technician for U-NASA's BUGS-2 project. During the BUGS-2 mission era, he delivered public lectures on Mars terraformation while secretly managing the mission's operations. He knew the crew comprised marginalized individuals, including criminals and the impoverished, selected due to the procedure's mere 30% survival rate.

Honda maintained communication with mission director Alexander Gustav Newton throughout BUGS-2's Mars expedition. He authorized Victoria Wood to eliminate Captain Davis if necessary and ordered the retrieval of a Terraformar egg for potential military use. This directive led to the egg hatching prematurely, causing the ship's crash and loss of contact with the crew. Newton later confronted Honda about the failed weaponization attempt, stating the Terraformars' evolution had surpassed human control.

Twenty years after the BUGS-2 failure, Honda lived undercover as a bartender in Saitama, Japan. His past was uncovered by Shichisei Hiruma of the Japan Self-Defense Forces. Hiruma noted Honda's earlier attempt to advance Japan's interests via his brother during BUGS-2 had failed but recruited him for the Annex I project due to his classified knowledge.

In the live-action film continuity, Honda commanded the surviving BUGS-2 crew to return to Earth with a Terraformar egg. When the egg hatched mid-transit, he ordered the ship back to Mars after witnessing the Terraformars develop wings. Following the mission's catastrophic outcome, he killed U-NASA official Sakakibara using a toxic spider to conceal their actions and then disappeared from society.

Physical descriptions note his transition from a young, light-haired man with glasses to an aged appearance characterized by thinning, slicked-back hair and a gaunt physique.