The protagonist of this anime is twelve-year-old junior high school student Hibari Hanakoganei living in Akihabara, a suburb of Tokyo in the year 2010. The current craze among young girls in Akihabara and probably all of Japan are electronic pets called “Pata-Pi.” Simply buy one, upgrade it with pre-set or custom parts, and show it off to friends and relatives! Hibari, however, seems to be the only girl in town who doesn’t have one and can only admire the PataPi owned by her best friend, Suzume, whom she has named Francesca and flamboyantly brags that he is “the best PataPi in the world!”
Late one evening, as Hibari is walking home, she sees a hill upon which a person is standing beside a tree at the peak and recognizes it as ‘her Prince’ (Crane) who has been appearing to her in her dreams. She runs towards him and he mysteriously vanishes. Suddenly a glowing sphere descends from the sky and lands on her palms. It materializes into a PataPi. She hugs it with all her heart. The adventure of Hibari and Densuke the PataPi begins.
Unbeknownst to Hibari is that she is under the watchful eye of a certain shadowy character and is ambushed when she walks home from school. Attacked by strange creatures called Homunculus and confronted by a (rather grotesquely endowed) masked woman (Jun), Hibari finds out that they are after Densuke and strives to protect him. When all else fails, Jun calls out a more powerful creature called Cerberus to attack Hibari and take Densuke from her. Out of extreme love for Densuke, Hibari cries out and an intense beam of light descends from the sky onto Densuke. Densuke vanishes and transformed into a woman in a black body suit to which various mecha components materialize and bond to her. Densuke has become the Diva (Aphrodite), who looks remarkably like Hibari. Aphrodite soundly defeats Cerberus while Jun runs away in defeated frustration. Unknown to Hibari, a masked man in black (Takashi a.k.a. Shooting Star) stands at the top of a building, observing every moment of what happened. Shortly thereafter Aphrodite vanishes, Densuke re-appears and falls to the ground as Hibari quickly scoops him up.
The next few episodes focus on unlocking the Diva within the other PataPies, notably Suzume’s Francesca and Tsugumi’s Tetsuro, with some subtle intervention by Takashi. It also shows how the three girls get along (with disagreements sometimes) and form the Cyberteam in Akihabara, aimed at stopping masked women and their Homunculus from terrorising the city of Akihabara. It should also be noted that along with Aphrodite, each of the other Divas bears a striking resemblance to its respective owner.
As the series carries on, a bit more of the plot is revealed (with the principal Washuu commenting on hazy stuff at the end of every episode). In subsequent episodes we are introduced to Kamome and Tsubame (who start off as an unknown enemy to the four girls until she is cured of her evil finally helps them). It is also revealed that Washuu is the founder of a Celtic organization called Rosenkreuz (Rose Cross in German) and he himself is Christian Rosenkreuz, hiding under the name of Washuu Ryuugasaki to carry out his agenda. He once worked for the famous alchemist Paracelsus and collaborated with a French man, Cigogne Raspailles, and a young American man, Crane Bahnsteik to invent a device that can grant immortality (Divas). However, due to their secrecy, none of their inventions is revealed to the world. After Crane discovers that inventions made by the world lead to World Wars and the implications of Divas falling into the hands of warmongers, he finally ran off to space in his invented space rocket, together with all the plans on the immortality project.
Later on, it is revealed that the transformation of PataPies into Divas is not one-sided. The owner of the PataPi can fuse with the Diva to form a complete Diva. This is only possible for those who are the chosen Anima Mundi and possess a pure and undefiled heart. Towards the end of the series, only Hibari and Tsubame fuse with their Divas; Hibari beginning in episode 17 and Tsubame during episode 21. In the movie, all five of the girls fuse with their divas just prior to the film’s climax in the Primum Mobile space fortress. The fact that Takashi is a clone of Crane, and used by Washu like a puppet to awaken the sleeping Divas in space (kept in Crane’s space fortress the Primum Mobile), causes Takashi to rebel and find his identity in the world, with the three women Jun, Miyama and Hatoko joining him.
Also towards the end of the series, Kamome’s grandfather, Shimabukuro Sengakuji, reveals everything he knows about Rosenkreuz (he was once a member), the concept of Divas, which are artificial forms powered by neutrinos, and the principal Washu who is the mastermind behind the events. Soon after, Washu discards his pseudo-identity, reverting to the original Christian Rosenkreuz, and changes the school into a large altar to welcome the descent of