Osakana wa Ami no Naka is a story based on manga by Nekokichi Ranma about Tsukamoto Yuuji, a young businessman and great swimmer, and Matsui Takahiro, who is still attending school and is also a beginner in swimming.

Mimu Emilton is a cute fourteen-year-old who has come to the annual Starland Festival to become an idol, just like her role model, Yuri. It is the most celebrated event on a united Earth, and Yuri, now the President of Earth, has encouraged people to join the ranks of Excellent Idols. Unfortunately for Mimu, she can never seem to make it to her audition on time, as misadventure after misadventure lands her in situations (usually involving undergarment exposure, I might add) that she escapes with the help of the current Excellent Idols, whom she befriends. Just as she makes her place on the stage and begins her audition, though, an unknown group of aliens kidnaps her and the Excellent Idols. It is only the beginning of a wild interdimensional goose-chase that places Mimu in the position to save the world, if only she can believe in herself.

At the end of the 21st century, a meteorite collision plunged Earth into apocalypse, and the remnants of humanity went in two different directions to survive. The aristocratic Dobias headed into space, while the earthy Shioru went underground. Centuries later, they returned to Earth's surface and are now fighting for control of the planet—that is, when they're not busy fending off a new species of predators known simply as Creatures. Amidst this conflict, an elite team of five soldiers known as Geisters protects humanity from the Creatures and from each other. Although part of the Dobias, the Geisters have recently accepted a soldier of Shioru descent onto the team, and her take-charge personality leaves the other members unsure about her loyalty and usefulness to the group. With Dobias and Shioru tensions heating up on the political floor, Creatures running rampant, and a dangerous new weapon being developed in secret, the Geisters must maintain peace among themselves and the rest of society.

Depiction of Japan's economy, based on Shoutarou Ishinomori's epynomous manga.