The anime follows a group of friends Giulia, Maria, Enrico, Lucio and Angelon during the disaster as they team up with a Japanese journalist Shiro Ando, and begin their own investigation of what's occurring (during the week long period of exposure when the ICMESA refused to notify citizens of the poison). As many animals are dying and people are getting sick. The children and Shiro discover deadly dioxin was released and inform Enrico's father, the town mayor, who evacuates all the citizens. Shiro continues investigating more and learns of the negligence of La Roche, a company who controls ICMESA. La Roche knew they were in violating of existing safety laws/protocols and destroyed evidence of their crimes. The children attend a press conference to ruin La Roche's reputation as the destroyed proof might not be enough in a court of law to punish them. Giulia's pregnant sister, who opted to not abort, gave birth to a healthy girl. The happiness is short lived, as the baby prematurely dies from dioxin poisoning.

After two-month-old kitten Chibi-neko is abandoned by her former owners, she is found by 18-year-old Tokio. Although his mother is allergic to cats and has a great fear of them, she agrees to let him keep the kitten because she fears he is becoming too withdrawn after failing his university entrance exams. Chibi-neko soon falls in love with Tokio. In her own mind, Chibi-neko is a small human who speaks in human words, although people only ever seem to hear her meow, and she believes that all humans were once kittens like her. A stray cat tells Chibi-neko of a paradise called Cottonland, where dreams can come true.

Hiroshi Shiba is an outstanding car racer whose father is assassinated upon the discovery of the Bronze Bell from an ancient civilization. This Bronze Bell is coveted by Queen Himika who comes from that ancient era; the Yamatai Kingdom, and whose ambitions are to seize the Bell and dominate earth. Hiroshi is left with a few items from his father which would enable him to morph into a full sized mecha warrior, the Steel Jeeg. With these abilities and the help of his father's brain implanted in a computer and his assistance Miwa "Micchi" Uzuki, they set out to neutralize Himika's plans of world dominion.

Mayfly reveals Cima's backstory in flashbacks as she reflects on her past prior to the events of Episode 13. It reveals that Cima and her unit poisoned a Side 5 colony using G-3 nerve gas, under orders, but were treated as pariahs afterwards by their own countrymen for committing such an atrocity. At the end of the war her superior refused to let her retreat to Axis. Because their home colony Mahal had been converted into a weapon, Cima and her men were left stranded and homeless.