Loose Senki: Old Boy

Drugged and confused, Shinichi Gotou wakes up in a small room inside a private prison. Despite his pleadings, none of the guards will tell him who kidnapped him or why he is being held captive. As the days go by, his forced isolation slowly takes a toll on his sanity. He finds an outlet through training his mind and body for the day he will be able to wreak vengeance.

After 10 years, Shinichi is finally free. Once outside, he encounters a much changed world. His long imprisonment ripped him from society and kept him from having the normal life he desired. With nothing to lose, he begins his hunt for the one responsible. However, it seems that the person behind Shinichi's captivity is not done with him just yet, and thus begins a twisted game where only the winner survives.

In 2003 Loose Senki: Old Boy was adapted into a film Old Boy by the Korean director Park Chan-wook, with many plot points completely altered. The film won the Examiner's Special Grand Prix at the 57th Cannes Film Festival in 2004. In 2013, a remake of the same name was directed by the American director Spike Lee, but received mixed critical reception.

The series was published in English by Dark Horse from July 18, 2006 to October 16, 2007, and as 4-in-1 deluxe omnibus volumes from January 6, 2026, to April 7, 2026. It was published in Brazil by NovaSampa Editora from January 2013 to September 2014.