Battle Fever Robo was prepared by the National Defense Ministry as Team Battle Fever's secret weapon against the Secret Society Egos. It was still under construction as Team Battle Fever was assembled and fought their first battle against Egos' Umbrella Monster. After the defeat of the Fang Lion Monster, Satan Egos, aware that a secret weapon was being developed but not knowing what it was, sent Commander Hedder and his Cutmen to acquire information on it by force but was foiled by Battle Fever. Following this, General Kurama Tetsuzan had Masao Den "steal" fake blueprints for the weapon, delivering them to an undercover Egos Monster while exposing a mole who revealed before being slain by the monster that Egos was developing their own giant robot.

In another attempt to uncover the secret weapon, Egos captured the researcher Segawa. Finding that their devices were not able to unlock the information from Segawa's mind, Satan Egos recruited the psychic Bengal Tiger to read his mind only to find nothing, proceeding to execute Segawa as he was of no use. Bengal Tiger would find, however, a connection in Keiko Nakahara.