Water World: From the Start, I Rescued Nine Girls from a Girl Group

The glaciers have completely melted, and 95% of the land is underwater. All that remains are scattered "floating island city-states," "undersea ruins," and "abandoned ports." Fresh water, food, and fuel are hard currency, while the oceans teem with mutated creatures such as giant octopuses, electric shark-eels, and ship-devouring jellyfish. Humanity's factions fall into three groups: marauding pirates, communities of survivors banding together, and the "Floating Island Alliance," which monopolizes resources.