Issei will stay dead for real however, Ophis will replace him as the new Issei.
The entire reason why Ddraig and Albion started a huge fight was to figure out if breasts or butts were better.
At some point in the near future, Issei will be on the ropes and about to die, when Rias will save him with her 'new' total obliteration move.
Issei's final and most powerful attack will be like the 00-Raiser Sword.
Chichigami-sama (the Breast God) is represented by none other than Paio II, the trope pantheon's goddess of boobies.
During the likely conflict against enemy vampires...
The next time Issei obtains a power up from Rias' breasts, it will cause Ryuutimaru (Issei's familiar which is a living ship) to evolve. Why, it might have a nude Rias as the figurehead at the prow
Gasper is the fifth illigitimate son of Dio BrandoWell, think about it, the power to stop time dosen't just drop out of the sky every day unless there was something special about your heritage. Stands in the universe of JoJo's Bizarre Adventure are hereditary powers that are passed from father/mother to child to future descendants, and the identical power of Dio's "The World" stand manifests in his most recent "descendant" Kujo Jotaro. In Gasper's case, he has internalized the power of his Stand rather than physically manifest it. Hence while the poor boy IS still a half-vampire, his father simply isn't who he thought it was. The double-stigma of being an illigitimate child on top of being an impure half human was what probably made the bullying suffered in childhood all the worse in the undead aristocracy. This would also explain his androgynously beautiful blonde appearance (which he got from Dio) and his sweet kind and Adorkable personality (which he got from Jonathan, whose body Dio stole).
The old man Issei met and changed his life to love anything breast related was an incarnation of Norio Wakamoto