In the second season of Senki Zesshou Symphogear, the Symphogear wielders embark on a mission to protect the crucial relic, Sacrist S, for both Irregular Threat Response and the American Federal Institute of Sacrists. As they escort this relic to an American military base, a dark storm unveils a new danger: the Noise. Despite teamwork between the two factions, the Noise threat multiplies from Babylon's treasury. Amidst chaos, Hibiki Tachibana's unique fusion with a relic unleashes a powerful song. With the Noise under mysterious control, a battle of songs and melodies ensues, revealing the girls' intertwined destinies.