  We present a dark sector model that reproduces the KOTO, MiniBooNE and muon
anomalous magnetic moment anomalies. The dark sector is comprised of a light
scalar singlet $S$ that has a large coupling to a slightly heavier sterile
neutrino that mixes with the active neutrinos. The scalar couples to standard
model fermions via Yukawa couplings, and to photons via a higher-dimensional
coupling. The KOTO signal is a result of the flavor-changing penguin process
$K_L \to \pi^0 S$ followed by the decay of $S$ to neutrinos. The sterile
neutrino produced in neutrino-nucleus scattering at MiniBooNE decays to an
active neutrino and $S$, which decays electromagnetically and creates an event
excess at low energies.
