Half a Confession introduces itself as a thriller and abruptly changes gears, transforming into a tale of morality with deeper insights into its characters than we had anticipated. It begins when Soichiro Kaji (Terao), a retired detective, walks into police headquarters and confesses to the murder of his wife. We learn that the victim had prematurely developed Alzheimer's after the tragic death of their son, and in her suffering, had asked to die. The police chiefs would be far more content to take him at his word if it were not for a conspicuous hole in his story: 48-hour gap between the alleged murder and his confession. Fearing a public relations nightmare, they are eager to bury the incident and keep the press in the dark.

Kaori is pursuing her career as a journalist for a magazine with great enthusiasm. But as a result of an article she wrote, she is sent to work for a community magazine at Fukuoka. An anonymous letter arrives, which puts her in contact with an old and forgotten theater, the 'Minato Theater' in nearby Shimonoseki.

The Straw Hats visit a recreational island, run by Baron Omatsuri, who asks them to complete a series of ordeals if they wish to stay on the island. Luffy accepts and the Straw Hats work together to complete them, but as the island's mysteries unfold, their lives and friendships are put to the test. It's up to Luffy to stop the Baron's plot and keep his crew together.