  We study a meson mass splitting due to isospin violation in holographic dense
matter. We work in a D4/D6/D6 model with two quark flavor branes to consider
asymmetric dense matter in holographic QCD. We mainly consider two cases. We
first consider $m^+/m^-\sim m_d/m_u$ to study the effect of isospin violation
on the meson masses. Then, we take $m^+/m^-\sim m_s/m_q$, where
$m_q\sim(m_u+m_d)/2$, to calculate in-medium kaon-like meson masses. In both
cases we observe that the mass splitting of charged mesons occurs at low
densities due to the asymmetry, while at high densities their masses become
degenerate. At intermediate densities, we find an exotic behavior in masses
which could be partly understood in a simple picture based on the Pauli
exclusion principle.
