User blog comment:B214/Volume 1 - 15 Discussion/@comment-1392308-20131103033005

I find Volumes 1-15 to be incredible. Volume 3 was a good way to start a new arc and Volume 7 was even better at kicking it off. Volume  was great for expanding the DxD world by going into other mythologys (even though 5 had already started that) and leading to Issei and Vali setting aside their differences and becoming allies (somewhat).

I found Issei's growth to be very interesting; he's definitely come a long way since the beginning.

Volume 1: Awakening his powers

Volume 2: Learning to use his powers

Volume 5: astering his Balance Breaker and becoming strong enough to face devils on his own

Volume 9: Surpassing the limits of his Sacred Gear by utilizing Triana

Volume 10: Finding an alternative to Juggernaut Drive--Cardinal Crimson Drive and achieving greater power

Volume 14: Learning to utilize Asaclon's aura to face off against dragons

He's come a long way and clearly works his butt off to obtain more power. He's definitly more fun to read about than Naruto (to me at least).