User blog comment:B214/Question and Answers/@comment-5882552-20130129053041/@comment-115.133.206.23-20130129113734

Rias' actual age has never been revealed, she could be older than we know, i mean Ravel did mention once that if she follows the age of the humans, she would be a first year student in Kuoh Academy. Well, the same could be said to Koneko, Akeno and Gasper.