In this article, we review three recently published experimental results of lepton flavor universality tests in semileptonic B meson decays based on the Run1 data sample of the Belle II experiment.
We present measurements of the branching fraction ratios $\mathcal{R}(D^{*})$ using hadronic B-tagging, alongside both $\mathcal{R}(D)$ and $\mathcal{R}(D^{*}) $ using semileptonic B-tagging. Additionally, we include the first inclusive probe of the $b \to c \tau \nu$ transition via $\mathcal{R}(X_{\tau / \ell})$ using hadronic B-tagging.
Finally, we summarize the current global experimental status and provide an outlook on the sensitivity prospects for the Run2 target 10 ab$^{-1}$ integrated luminosity.