Loose Senki: Old Boy

Summary

Ten years ago, they took him in. He doesn't even know who. And for ten years, he has been confined in a private prison. He doesn't know why. For ten years, his only contact with the outside world has been a television set and the voices of his jail mates. In time, he lost himself. He changed...transformed himself into something else...something hard...something lethal. Suddenly, one day his incarceration ends, again without explanation. He is sedated, stuffed inside a trunk, and dumped in a park. When he awakes, he is free to reclaim what's left of his life...and what's left is revenge. (Source: Dark Horse)