User blog comment:B214/Question and Answers/@comment-80.117.124.108-20130101142245/@comment-80.117.202.62-20130102190540

then if Issei was a "pure dragon" before Rias "reinserted" the Evil Pieces, he have the same "lifespan situation" of Tannin since Tannin was a pure dragon too,... so if Tannin have a limitless lifespan than Issei have too, the thing is like this, it's not like change since both was a pure dragon and both of them was reincarnated as devil