Police on Saturday arrested a fifth man in connection with the confinement of a woman for three months in Takamatsu, Kagawa Prefecture.
Atsufumi Izumi, 25, allegedly held the 23-year-old woman at a house after they had argued over a car deal between Feb. 8 and Thursday, the police said.
The man turned himself in to police on Saturday following the arrests Friday of four male accomplices, police said.
The police sent to public prosecutors the cases against the other four -- Kazutaka Maeda, 22, Hitoshi Nishinaka, 21, and two minors aged 18 and 16 -- on suspicion of being involved in the confinement. The two minors cannot be identified under Japanese law.
All are being questioned by the police, who suspect that several others were also involved in the incident, they said.
The police believe the five men who have been arrested beat the woman around the head and arms using a golf club and a wooden bar.
They allegedly took turns to guard her in a room on the second floor of the two-story house.