Japanese police have arrested a 73-year-old man who reportedly kept his disabled son in a small wooden cage for more than 20 years.
Hyogo prefectural police said they arrested Yoshitane Yamasaki and sent him to prosecutors for further investigation.
Police said Yamasaki kept his son, now 42, in the cage inside a hut next to his home in Sanda City until January, when he turned himself in to city officials.
The officials visited his home and found the son sitting inside the cage, slightly bigger than a coffin.
He has since been in the care of a welfare centre.
Yamasaki told police he started confining his son when he became violent years ago.
Japanese media said the son was caged for more than 20 years, but police would not confirm that number.
Due to years of confinement in the one-metre (3ft) high cage in which he could not stand up, the son's back was bent and he was nearly blind because of infections from the filthy conditions, according to the Yomiuri newspaper and other Japanese media reports.
Police said they were still investigating and declined to give details about the son's condition, except to say that he had no life-threatening injuries or illness and has since been cared for by a welfare centre.
Police are also looking into whether neighbours did not notice his confinement and why it was unreported for so long if he had been violent and noisy.