Masahiro Nakai, one of Japan's top TV hosts and a former pop star, says he is retiring to take responsibility over sexual assault allegations.

Japanese TV host Masahiro Nakai, one of the country's most recognisable faces on television, announced on Thursday that he was retiring after a sexual assault allegation that has rocked the country's entertainment industry.

Nakai’s decision came following reports that he engaged in non-consensual sexual activity with a woman that led to a settlement with the victim.