

"Why did I open the window that night? If I had not, I'd never have needed to know what it is like to fight, starve, or suffer in anguish." Shion has been raised here as a high-ranking elite since the age of two, but on the night of his twelfth birthday his fate is turned upside-down when he meets a boy who calls himself Nezumi. 6, the city that embodies the highest ideals of humankind.

Karan (Rico's sister) ( カラン ) Voiced by: Megumi Nakajima Safu's Grandmother ( 沙布の祖母 ) Voiced by: Miyoko Shouji Shion begins to find out the hidden truth behind the Ideal City No.6. Whilst Shion is being transported to the Correctional Institute, Nezumi appears and rescues him. Shion's co-worker is one of the victims and Shion is arrested on suspicion of murder. Four years later, Shion experiences a spate of incidents around him in which a deadly infection by parasitic wasps leaves its victims to age rapidly. After spending a rainy night with his new friend, Shion discovers the next morning that Nezumi has left and disappeared without a trace. Shion, a boy raised in the elite and privileged environment of his home, gives shelter to another boy, who only gives his name as 'Nezumi', during the former's 12th birthday. The story takes place in an ideal city known as "No.
