Test of Lepton-Flavor Universality in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mo>*</mml:mo></mml:msup><mml:msup><mml:mo>ℓ</mml:mo><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mo>ℓ</mml:mo><mml:mo>−</mml:mo></mml:msup></mml:math> Decays at Belle

We present a measurement of $R_{K^{\ast}}$, the branching fraction ratio ${{\cal B}(B\to K^\ast \mu^+ \mu^-)}$/ e^+ e^-)}$, for both charged and neutral $B$ mesons. The case, $R_{K{^{\ast +}}}$, is first ever performed. In addition, we report absolute fractions individual modes in bins squared dilepton invariant mass, $q^2$. analysis based on data sample $711~\mathrm{fb}^{-1}$, containing $772\times 10^{6}$ $B\bar B$ events, recorded at $\Upsilon(4S)$ resonance with Belle detector KEKB asymmetric-energy $e^+e^-$ collider. obtained results are consistent Standard Model expectations.