Kouichi Madanbashi, a high school student whose self-proclaimed perversion centers on an unabashed fixation with women’s breasts, wields the unique capacity to generate Hi-ERo particles—energy essential for operating the robotic weapon Daimidaler. Activation requires physical contact with female characters, most notably through groping Sonan Kyōko’s breasts, intertwining his carnal impulses with combat necessity as a pilot. Initially resistant to Kyōko’s recruitment against the Penguin Empire, he embraces his role upon discovering both his aptitude for piloting and his enjoyment of their charged interactions. His personality thrives on blunt, unrestrained expression, disregarding social norms to voice his desires openly. Though his lewd antics provoke friction, they forge a layered dynamic with Kyōko, whose reluctant attraction grows despite his transgressions.

Presumed dead after sacrificing himself to shield Kyōko from an enemy robot’s self-destruction, he survives via Hi-ERo particle-induced teleportation to the Penguin Empire’s dimension. There, allied humans restore and enhance Daimidaler, enabling his return to Earth by synchronizing with the machine’s remnants—a testament to his adaptability.

Academically linked to fellow pilots Kiriko Kiyuna and Shōma Ameku as their underclassman, his presence amplifies tensions between societal judgment of his overt sexuality and the public romantic displays of his peers. Media iterations consistently position him as a source of comedic and plot-driven strife, with age adjusted between 16 (manga) and 17 (anime) without altering core traits. His surname, etymologically rooted in terms for "genuine," "sphere," and "bridge," mirrors his role as an interdimensional conduit and unvarnished persona.

Post-return storylines escalate Daimidaler’s capabilities and pivot toward large-scale clashes involving Japan’s military and the Penguin Empire’s agenda, cementing his centrality to the series’ expanding conflicts even as new players emerge.