User blog comment:B214/Question and Answers/@comment-5882552-20130129053041/@comment-1359322-20130129114804

The Devils can live for around 10,000 years old, so we can't compare the humans age and Devils age. The same can be said for other supenatural species. I mean for all we can know maybe even Gasper and Koneko is older than Issei in age.