Nabari no Ou Vol. 3 (manga)

The Hidden World seems less and less hidden as Togakushi Village approaches the ninjas of Banten with a proposition: In return for their help in taking out an eminent scientist-turned-weapons developer in the surface world, Togakushi will hand over their forbidden art scroll. But this job offer comes with strings attached as Togakushi’s mind-reading chief holds Banten’s deepest, darkest secrets hostage and threatens to reveal all if they refuse to play nice! Will Kumohira-sensei’s decidedly peace-loving way of the ninja allow him to cover his hands in blood?!