Masamune Kuze emerges from the expanded media of the franchise as a Solon citizen aligned with Victor Yeager’s faction, a group desperate to salvage their dying populace amid clashes with the Draktors. His name carries layered symbolism: "Masamune" blends "government" and "essence," while "Kuze" merges "long time" and "world," echoing his role as an ideological leader within Solon’s struggle.

Driven by Solon’s crisis, Masamune spearheaded a coup against Oblivion Bay by seizing the Landeye facility, aiming to secure vital resources for his people’s survival. This aligned with Victor’s agenda, leveraging stolen Ixia technology to replicate the Musashi-O mecha—a derivative of the original Musashi. Masamune piloted this prototype before infiltrating Ixia, relinquishing control to Victor.

Though defeated by Teru and Ryuji, the coup’s fallout prompted Oblivion Bay to permit Solon’s integration with Ixia. Masamune later joined Oblivion Bay as a pilot, commanding the Fire Loader—a high-mobility mecha engineered for heat resistance and adaptive combat. The unit integrated Draktor-derived data, refining its attack versatility to match his aggressive tactics.

His journey traces a path from desperate antagonism to reluctant alliance, mirroring Solon’s fraught assimilation into broader resistance efforts. The conflict between Victor’s faction and other survivor factions underscores the fragile alliances and ideological rifts complicating humanity’s stand against the Draktor threat.