So I Am A Demon Descendent!

My name is Li Xianyu, and in this era where time travel and rebirth have become incredibly common, I inherited my father’s inheritance: a great-grandmother! As it turns out, she isn't just an ordinary person; she is a powerful, ancient war spirit who emerged from my father's will.

My father left me a letter explaining that I am a descendant of ancient demons and that my worldview is only the tip of the iceberg. To uncover the truth about this hidden, mystical world, I must undergo an integration of flesh and spirit with my great-grandmother to awaken my bloodline. But how exactly am I supposed to 'develop' a great-grandmother who acts more like a teenager craving snacks from twenty years ago than an ancient entity?