So I Am A Demon Descendent!

When Li Xianyu was 20 years old, he received his father’s inheritance, an 18-year-old great-grandmother who was incredibly beautiful.
Li Xianyu: “Great-Grandma, why are you so young?”
Great-Grandma: “That’s because I died when I was 18 years old.”
Li Xianyu: Σ( っ° д°;)