  We propose a quark-lepton model via leptoquarks and modular $A_4$ symmetry.
Since the neutrino mass is induced at one-loop level mediated by down quarks as
well as leptoquarks, we have to explain lepton and quark masses and mixings
with a single modulus $\tau$. Here, we find predictions for lepton and quark
sectors with unified modulus $\tau$, and show several constraints originating
from leptoquarks.
