User blog comment:Crimson and Darkness/DxD Updates 2~/@comment-27083298-20170625115044/@comment-31137559-20170626160714

Just that Saji happened to have sex with Sona. Volume 17 was at the beginning of December I believe. And now it's summer. He could have confessed to her after the Auros Academy incident and she returned his feelings. And they entered a secret relationship and after a few months, just had sex. And Saji doesn't suffer from MCitis like Issei does so it's all good. He's a side character so it really wouldn't affect the story if he 'climbed the steps to adulthood' before Issei did. Would be hilarious if Saji revealed his secret relationship with Sona and revealed they had sex thinking that Issei already had sex with Rias only to be shocked when Issei told him he's still a virgin. XD