In the morning, as Saya comes into her classroom, she finds a blue rose.

Students are murmuring about the phantom legend that has been the gossip at the lycee. Saya and Hagi sneak into a rose garden beside the church where it is said the blue roses were in bloom. And they find steps leading to the underground...

Saya and Hagi arrived at the ruins of "The Zoo," were Saya's forgotten past is sleeping. The place is covered with overgrown grass and only a portion of the exterior walls is still standing. Soon, Saya's memories awake: her first encounter with Hagi, the incident on the Zoo owner's birthday, and the image of the whole building on fire...

It has been one year since Diva's attack on the Red Shield Headquarters. Kai and the others stay with David's old comrade in the outskirts of London. Passing time brings various changes to everyone. But again, the Chiroptera overshadow the streets of London...