Hobbies are often a great way of meeting new people, but how could Kakeru Diachi, who collects rare juice cans, have ever suspected that he'd meet a fascinating new girl when he attempted to DRINK her? Naming her Melon, because she's got great melon... soda, Kakeru quickly learns that she's an Akikan—a beautiful girl who's also a special can created to fight other Akikans in a strange experiment to determine what kind of container is better: steel or aluminum! Will becoming involved in this ridiculously twisted research project gone amuck complicate Kakeru's life incredibly? Of course it will, but because Melon's steel body needs carbon dioxide to breathe, he's now stuck with her since she's too CO2 dependent! And when his wealthy, attractive, best childhood friend Najimi gets HER own aluminum Akikan, the trouble really begins!

Haruka Kiyomine and Kei Kaname were once recognized as the most formidable pitcher-catcher duo in middle school baseball. Known as the "General," Kaname paired his expert strategies with Kiyomine's explosive pitches, crushing the dreams of many starry-eyed players who hoped to one day make it to the big leagues. High school freshman Tarou Yamada is one such former player. Having given up on competing, he enrolls in Kotesashi High School—a completely average public school with no baseball team to speak of—where he discovers that his new classmates are the legendary pair who once destroyed his dreams. Adding to this shocking revelation, he learns that amnesia has reduced the once level-headed General to a vulgar class clown. Having lost all interest in baseball, Kaname dragged a disappointed Kiyomine to Kotesashi simply because the school was close to where they live. As Kotesashi forms a fledgling baseball club, Yamada meets other players he once admired who also left baseball behind. While they might be unwilling now, Yamada believes that if he can convince such talented athletes to start playing again, it might be possible to achieve their dreams and win the national championship—as long as they can put up with Kaname's incessant joking.

Once upon a time, a race known as the Shadow Angels attacked Earth to harvest the life force of all those who inhabited the planet. Thanks to some outrageous miracle, the Shadow Angels went dormant, and humanity was able to live another 12,000 years without fearing their presence. But 11 years after a catastrophe dubbed the Holy Genesis brought ruin to the Earth, the Shadow Angels were stirred from their slumber and resumed the attacks once more. To give humanity somewhat of a chance, an organization known as DEAVA was formed, and use of a robotic weapon named Aquarion has been authorized. In order for the Aquarion to be brought to full power, three pilots must combine their hearts, bodies, and souls into one—a feat few can hope to accomplish. Thus, the search for so-called 'Element Users' was prioritised, hoping to ensure humanity's future. Sousei no Aquarion follows the story of Apollo, a near-feral young man brought up in poverty, who is believed to be a legendary hero reincarnated. After his best friend is taken by the Shadow Angels, Apollo chooses to become an Aquarion pilot. Will he be able to turn the tides of the war, and free humanity from the threat of the Shadow Angels for once and for all?