A young singer dies and becomes a zombie. She is put in a musical group with other zombie singer girls as part of a campaign to save the world.

In a flooded world, nations form "Azur Lane" to fight "Sirens". Factions "Union", "Royal", "Iron Blood", and "Sakura Empire" wield anthropomorphized warships from a "Wisdom Cube".

After his mother's death, a piano prodigy's will to play disappears. But meeting a free-spirited girl who plays the violin turns his life around.