Kain (manga)

Kain (カイン, Kain) is a Japanese manga series written and illustrated by UCHIMIZU Tooru.

Plot
Kain is a story about a blue-eyed boy wandering the countryside. He happens to be in a town controlled by "kidoushi." These kidoushi are people from the newborn country of Ren, who have a machine in their body, giving them power equal to an army in return for pain proportionate to that power. The power of the kidoushi is determined by the amount of gigai (the machine) taken up in their body.