Maou09
the life spans are perfect, I gotta the feeling isseis about to make it so Humans ain't the weakest anymore because let's face it without good resources, weapons or sacred gears humans are the weakest and cultivation is the perfect tool for them to stop being the weakest, especially because they can start to live as long as they do
Will you use things like sacrificial techniques because I can't find another reason to add the lifespans gained from different cultivation realms as the canon story of DxD happens in less than 30 years, unless you're planning to add another story into the ff as the future of the timeline (like "The Irregular at Magic High School" as a future of you ff) or you're planning to send Issei to the past or something like that