The mutilations are frightful — dog, cat, rabbit and pigeon corpses missing heads, tails, limbs, ears. Weekly Playboy magazine reports nearly 40 sightings in the past four months in the Kanto region alone. Who's out there doing these things? With what thoughts in mind?

Anyone familiar with an old but not forgotten murder case will immediately recall — as Playboy does — "Seito Sakakibara," aka "Boy A," who, after a childhood history of torturing cats, killed two children in Kobe in March 1997. When police finally caught up with him three months later, they were astonished to find themselves dealing with a 14-year-old. His obvious intelligence, and the depth of his perversion, suggested adulthood at the very least.

Boy A is not a boy any more; he's 32 and at liberty somewhere under a new and secret identity, having been pronounced rehabilitated in 2005. This past June he surfaced, to the extent one can surface anonymously and invisibly, as the author of an autobiography, in which he describes at length the quasi-sexual thrill he got as a child from tormenting helpless animals. Tortured cats, he writes, scream like newborn babies.