User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-2602:306:CD9A:C860:ADF7:BBD3:E780:15AC-20171206031730/@comment-2602:306:CD9A:C860:ADF7:BBD3:E780:15AC-20171206205132

Oh you think so? From what I've read from spoilers Rias can't maintain the form for long do to the strain it puts on her body so might Issei win base on that because he has no stamina issues in Cardinal Crimson anymore.