Kyosuke Nanbu stands as a central figure within the *Super Robot Wars* narrative continuity. His defining history includes surviving a pivotal shuttle crash in his youth, one of only two survivors. He shielded Excellen Browning from debris during the event, which left him imbued with unnatural luck. This luck enables survival against fatal odds, like emerging from the Wildraubtier's destruction during a test run with only broken ribs.

Beginning as a test pilot, Sanger Zonvolt recruited him into the Earth Federation Army's ATX Team. When Sanger defected to the Divine Crusaders, Kyosuke ascended to ATX Team leadership. He maintains a stoic, reserved, and emotionally detached exterior, often appearing indifferent—a stark contrast to his partner, Excellen Browning. Despite this demeanor, he harbors deep care for Excellen, and threats to her provoke intense, focused rage. His personality features a habitual gambling streak, frequently framing battles as high-stakes wagers with lives on the line, encapsulated by his catchphrase: "I don’t mind betting on tough odds."

In combat, Kyosuke specializes in close-quarters engagements, piloting the deliberately bulky, mechanically demanding real robots Alt Eisen and its upgraded form, Alt Eisen Riese. These units, designed with his input and tailored to his style, prioritize raw power and durability over agility. He employs a head-on, tank-like approach, leveraging heavy armor and weaponry to absorb damage while closing distance. His tactical acumen allows swift decisions under pressure, and his combat style often incorporates devastating counter-attacks, exploiting openings created by enemy assaults.

His journey spans multiple conflicts. During the Divine Crusaders War, he solidified his role as ATX leader. Subsequent events saw him clash fiercely with Axel Almer of the interdimensional Shadow Mirror faction, nearly destroying the Alt Eisen and spurring the development of the Alt Eisen Riese. Later, the extradimensional Einst targeted him as a potential "Adam" for their plan to remake Earth, manipulating Excellen against him. Kyosuke resisted their influence, freed Excellen, and helped defeat the Einst.

A significant emotional arc unfolded during the ODE Incident involving Lamia Loveless. Failing to prevent her apparent capture and presumed death plunged him into profound guilt and despair. Resolution came when Axel Almer, now an ally, rescued Lamia, leading Kyosuke to reconcile their rivalry and vow repayment.

Following these events, Kyosuke became dimensionally displaced during a training exercise. Transported with Ryusei Date to the world of Eria, they later separated; Kyosuke emerged in the subterranean realm of La Gias. There, he reunited with allies like Lune Zoldark and encountered new figures such as Hwang Yang Long, engaging in conflicts against factions like the Gaia Sabers and Garden of Baral.

A notable alternate version exists in the Shadow Mirror universe, codenamed Beowulf. This Kyosuke pilots a blue Gespenst Mk III, exhibiting ruthless, sadistic traits after murdering the SRX Team in his world. Possessed by the Einst, he sought to destroy and rebuild realities, invading the primary universe before defeat by the combined efforts of the Earth Federation Army and Axel Almer.

Throughout his journey, Kyosuke forms lasting bonds, particularly the deep personal connection and complementary combat partnership with Excellen, rooted in their shared survival. He also mentors younger pilots like Bullet Luckfield, channeling his disciplined approach into guiding the next generation.