Mirzakhani-Zograf proved the large genus asymptotic expansions of Weil-Petersson volumes and showed that the asymptotic coefficients are polynomials in $\mathbb Q[π^{-2},π^2]$. They also conjectured that these are actually polynomials in $\mathbb Q[π^{-2}]$. In this paper, we prove Mirzakhani-Zograf's conjecture.