  Building an organized Yukawa structure of quarks and leptons is an essential
mission to understand fermion mass hierarchy and flavor mixing in particle
physics. Inspired by the similarity of CKM and PMNS mixings, a common mass
pattern for up-type and down-type quarks, charged leptons, and Dirac neutrinos
is realized in terms of hierarchal masses. An organized structure of Yukawa
couplings can be expressed on a Yukawa basis. The CKM mixing and PMNS mixing
have the same mathematical forms due to $SO(2)$ family symmetry. By fitting the
CKM/PMNS mixing experiment, the flat pattern becomes a successful flavor
structure. The fundamental fermions can be explained by a new picture to show
the relationship between gauge structure and flavor structure.
