User blog comment:Crimson and Darkness/Shin DxD 3 discussion/@comment-2208155-20190822124247/@comment-10330822-20190823064642

You're mistaken, Akeno won't necessarily be the first time, she's just the first to get pregnant. Remember, purebloods like Rias are more difficult to get pregnant than mixed-bloods, humans, and fallen angels.

The concept is that Rias will have his first time, Akeno will give birth to his first child and his first son, and Asia will give birth to his first daughter.