A pair of mysterious voices lead 14-year-old Ai Ohto to a strange egg, promising her a chance at what she wants most. What's inside the egg? And what does Ai really want?

Ai meets Neiru, another girl who is buying Eggs. She's given the cold shoulder at first, but could that change after the next time they crack their Eggs? Assuming they make it back alive, that is.

While buying Eggs for herself and Neiru, Ai meets Rika, a former idol who is there for the same reason. Rika quickly pushes her way into Ai's life, but what lies beneath her cheerful and callous exterior?

With Rika out of action, Ai is on the run and struggling to protect two girls from the most devious killer she's faced yet. Meanwhile, a fourth child is also fighting to protect the girls in the Eggs.

Ai, Neiru, Rika, and Momoe are quickly becoming close friends as they continue to protect Eggs. But as they grow closer, questions pile up and tensions rise.

It’s Rika's birthday, and the girls get together to celebrate. Rika, however, is focused on her troubled relationship with her mother, and those worries carry over into her next battle. Will she be able to overcome her inner demons in time?

The girls realize that there's more waiting for them at the end of missions than they bargained for. As doubts pile up and tensions rise, Ura-Acca decides to tell Ai his story.

Friendships are tested as Ai and Neiru realize how much "victory" has cost Rika and Momoe. Ai decides to fight again in spite of what she's learned, but the girl who emerges from her Egg this time may be more than she bargained for.