While the move aims to encourage active social participation by youth, there are also concerns they will become easy targets for scams.
As adults, 18- and 19-year-olds may legally enter into consumer contracts without parental consent.
Changes to Japan’s Juvenile Law to implement stricter punishments for 18- and 19-year-old criminal offenders also came into effect April 1.
The revision expands the range of crimes where 18- and 19-year-olds are referred to prosecutors from family courts and tried as adults.
The revision also relaxes rules for media reporting, allowing for the full names and faces of 18- and 19-year-old offenders to be revealed.
With the lowering of the adulthood age, many related laws including those on passports, national licenses and jury duty have also been revised, but people under 20 will still be prohibited from drinking alcohol, smoking and gambling.
The Civil Code revision also lifts the legal age of marriage for women to 18.