Psycho-pass: Inspector Shinya Kogami Volume 6

The perfect society and its price...the manga prequel to the acclaimed anime series!
In the 22nd century, the Psycho-Pass is a system that measures emotional health, making crime not only rare, but strange and dangerous--and the only "safe" job for a person on the borderline is as a cop...kept on a virtual leash as they hunt down the criminals they may soon become themselves!
The explosive conclusion! As Division 3 races to try to save the life of Professor Toshi, they find that the trauma unit within the Special Sector has become a deadly trap. But in this high-tech underground complex, it's a hidden cache of a very obsolete information storage format--handwritten letters--that may provide the last clue that must be understood by Inspector Kogami...before the elders behind this hidden kingdom of guilt decide to carry out their final act of atonement!