Sim. A JAL, por exemplo, permite viagens não acompanhadas a partir dos 5 anos de idade.
What age does my child have to be to qualify as an unaccompanied minor?
Unaccompanied minor service is mandatory for a child age 5-11 traveling without an adult. Children ages 12-17 years are not required to travel as unaccompanied minors, but the service is optional for this age group as well.
Children under 5 years of age are not allowed to travel unless accompanied by an adult