Japan's age of consent was raised from 13, among the world's lowest, to 16 years old on Friday as lawmakers passed key reforms to sex crime legislation.

A new bill – which also clarifies rape prosecution requirements and criminalises voyeurism – cleared parliament's upper house in a unanimous vote.

The age of consent – below which sexual activity is considered statutory rape – is 16 in Britain, 15 in France, and 14 in Germany and China.

Japan's had been unchanged since 1907, with children aged 13 and above deemed capable of consent.

In practice, across many parts of the country, regional ordinances banning "lewd" acts with minors are sometimes seen as effectively raising the age of consent to 18.

Under the new law, teen couples no more than five years apart in age will be exempt from prosecution if both partners are over 13.

Japan last revised its criminal code on sexual offences in 2017, for the first time in more than a century, but campaigners said the reforms were insufficient.

And in 2019, a string of acquittals in rape cases triggered nationwide rallies.

Under the previous law, prosecutors had to prove victims were incapacitated due to violence and intimidation. Critics argued that requirement effectively blamed victims for not resisting enough.

The bill that passed on Friday contains a list of examples under which rape prosecutions can be made.

These include victims being under the influence of alcohol or drugs, being frightened, and perpetrators taking advantage of social status.

The bill also contains a new "visitation request offence", according to the justice ministry. It means that people who use intimidation, seduction or money to coerce children under 16 to meet for sexual purposes will face a prison sentence of up to a year or a fine of US$3,500. (AFP)