User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-95.210.189.106-20180405123805/@comment-86.149.140.107-20180406233117

If you think about it Issei not really a Devil after his rebirth becuase his flesh is 100% Dragon god and he does not have a Devil Soul because he was never a natural Devil the only thing that makes him a Devil is his Evil Pieces that are being warped and twisted by his Dragon powers.