  The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$ collider
is a substantial upgrade of the B factory facility at the Japanese KEK
laboratory. The design luminosity of the machine is $8\times10^{35}\,
\mathrm{cm}^{-2}\mathrm{s}^{-1}$ and the Belle II experiment aims to record
$50\, \mathrm{ab}^{-1}$ of data, a factor of 50 more than its predecessor. From
February to July 2018, SuperKEKB has completed a commissioning run, achieved a
peak luminosity of $5.5 \times 10^{33}\, \mathrm{cm}^{-2}\mathrm{s}^{-1}$, and
Belle II recorded a data sample of about $0.5\, \mathrm{fb}^{-1}$. In this
presentation we show first results from studying missing energy signatures,
such as leptonic and semileptonic B meson decays based on this early Belle II
data. We report first studies on re-measuring important standard candle
processes, such as the abundant inclusive $B\rightarrow X l \nu$ and $B\to
D^*\ell\nu$ decays, and evaluate the performance of machine learning-based
tagging algorithms. Furthermore, we also present an overview of the
semileptonic B decays that will be measured in the upcoming years at Belle II
and discuss prospects for important B-anomalies like R$(D)$ and R$(D^*)$, as
well as other tests of lepton flavor universality.
