"Senjō no Valkyria 3: Ta ga Tame no Jūsō" is a tactical role-playing game adaptation set in the fictional continent of Europa, during the Second Europan War. The story centers on Squad 422, also known as the "Nameless," a penal military unit composed of soldiers deemed expendable by the Gallian army. The Nameless are tasked with undertaking dangerous missions that regular forces avoid, often facing insurmountable odds and high casualties. The narrative explores themes of redemption, sacrifice, and the harsh realities of war.

The protagonist, Kurt Irving, is a former Gallian military officer who is demoted and assigned to the Nameless after being falsely accused of treason. Despite his circumstances, Kurt remains a skilled and principled leader, striving to protect his comrades and complete their missions. Alongside him are two key characters: Riela Marcellis, a kind-hearted and determined soldier with a mysterious connection to the ancient Valkyrur race, and Imca, a stoic and battle-hardened Darcsen warrior seeking vengeance against the Empire for the destruction of her village.

The plot unfolds as the Nameless are drawn into a larger conflict involving the Empire's secret weapon, the Valkyria of the Shield, and the Gallian military's own hidden agendas. The squad's missions take them across war-torn landscapes, where they encounter both allies and enemies, including the enigmatic Calamity Raven, a rogue unit with ties to the Empire. As the story progresses, the Nameless uncover the truth behind the war, the Valkyrur's legacy, and their own fates.

The narrative is structured around a series of missions that highlight the squad's struggles and growth, interspersed with character-driven subplots that delve into their personal histories and motivations. The interplay between Kurt, Riela, and Imca forms the emotional core of the story, as their relationships evolve amidst the chaos of war. The series balances tactical gameplay with a rich, character-focused storyline, offering a compelling exploration of the human cost of conflict and the bonds forged in its crucible.