An unemployed man has been arrested for confining a 19-year-old woman for 29 days in his family's home in the city of Miyazaki after she tried to break off their relationship, and his parents who were present never tried to help her, police alleged.
Police said the family of suspect Yoshinori Sakamoto, 28, feared he would become violent if they had stepped forward.
Sakamoto has denied confining the woman, who is from Kuwana, Mie Prefecture, police said.
She was not injured.
Police alleged that Sakamoto threatened the woman, with whom he had been dating, with a kitchen knife around June 5 when she tried to cut off their relationship.
He drove her to his home and threatened to kill her if she tried to escape, police alleged.
The confinement came to light when the woman escaped and sought help from a nearby shop when Sakamoto went outside to help with a relative's business at around 12:50 p.m. Monday, police said.
Sakamoto was living with his 58-year-old mother and 56-year-old stepfather.
Sakamoto's mother, who had seen the woman in the house, didn't want to get involved and thus turned a blind eye to the confinement, according to police.
