A group of teens in the 23rd century are stranded in an intergalactic spaceship and must make the journey home by themselves.

The year is AD 2225. Kouji Aiba and Aoi Housen are serving as astronauts in-training in Liebe Delta which is located on the edge of the Geduld Sea. When saboteurs with unknown intents suddenly strike during a routine dive procedure, the space station plummets into the Geduld, a plasma field that links all the planets like a nervous system and crushes any ship that strays too far into it. With all the adults onboard killed, the young astronauts will have to survive this long journey home in midst of the growing tension amongst each other. Meanwhile the organizers of the sabotage look on and prepare to attack once more.—Anime News Network

In the year 2137AD, a tremendous solar flare kills millions and spreads a dense plasma called the Sea of Geduld across the solar system. It is now 2225AD and teenage cadets learn to navigate around this deadly obstacle at a training center on the edge of the Geduld Sea. But an act of sabotage during a routine dive procedure sends the space station plummeting into the Geduld. With all the adult crew and instructors killed during the evacuation, the young astronauts can only rely on their training and each other to survive the journey home.-esteem.—Sunrise