User blog comment:B214/Shin DxD 1 discussion/@comment-2A01:E35:8A27:B990:CDFF:A237:45B5:A954-20180721100147/@comment-34061653-20180722003702

How do you know she didn't compete in that 30 year time gap? Rias likely started her career in professional rating games after she graduated from college which would just take her 4 years and spent several more years in the professional league before retiring to focus on her business career.