Exotic and Conventional Quarkonium Physics Prospects at Belle II: Search for a Partner State to the $X(3872)$ at the $D^{\ast 0}{\bar{D}}^{\ast 0}$ threshold

The Belle II experiment at the SuperKEKB asymmetric $e^{+}{e}^{-}$ collider at KEK, Tsukuba, Japan, is recording data since 2018. The expected high luminosity of $\mathcal{L}=8\cdot {10}^{35}$cm${}^{-2}$s${}^{-1}$ enables searches for yet unobserved exotic hadronic states in B meson decays. We describe the search for a partner state of the $X(3872)$ at the $D^{\ast }{\bar{D}}^{\ast 0}$ threshold. The reconstruction of charmed mesons is tested with experimental data corresponding to an integrated luminosity of $504$pb${}^{-1}$ collected at the energy in the center of mass of $\mathrm{{\rm Y}}(4S)$ in 2018, and $2.62$fb${}^{-1}$ in 2019.