  Flavor specific scalar bosons exist in various proposed extensions of the
Standard Model and are motivated to couple to single generation of fermions
through a global flavor symmetry breaking mechanism. We propose the MeV flavor
specific scalar model in an effective field theory approach, where muon g-2
anomaly and proton radius puzzle can be explained remarkably through the
coupling with muon and down-quark simultaneously. The framework is consistent
with the null result of high intensity searches. In particular the E137
constraint is safely ignored by assuming mediator decaying into sub-MeV dark
matter dominantly. The existence of sub-MeV dark matter results in
over-production of dark matter and $\Delta N_{\mathrm{eff}}$ constraint, which
can be solved by introducing additional Majoron mediator. We also investigate
the searches for mediator and dark matter and their implications on viable
parameter space such as supernova cooling on muon coupling, atomic physics
constraint, direct detection for light boosted dark matter.
