Please don't drop, I very much enjoy the story and also hit the refresh to check for updates!

Additionally, Senjutsu is incredible at healing both mind and body showcased with Rias using Bouchujutsu (Bedroom Method) healing Issei and Naruto using Yang Chakra to healing both Guy and Kakashi.

Try looking up Senjutsu (Sage Art/Techniques) as its known to be a method of achieving immortality and its used in both Highschool DxD (Bouchujutsu) and Naruto (Six Paths).