Reborn in Konoha; I Think I’m Cultivating Immortality Novel

A teenager succumbs to a terminal illness, only to awaken in the Naruto world during the era preceding the first great shinobi war. Stripped of the system he'd dreamed of, he discovers something far more valuable—a body capable of perpetually absorbing an energy vastly superior to Chakra. With time as his only constraint, he embarks on an unlimited cultivation journey toward immortality.