  This is the part II of a two-part work started in arXiv:0807.3356 [math.QA].
In part I, Cardy algebras were studied, a notion which arises from the
classification of genus-0,1 open-closed rational conformal field theories. In
this part, we prove that a Cardy algebra also satisfies the higher genus
factorisation and modular-invariance properties formulated in
arXiv:hep-th/0612306 in terms of the notion of a solution to the sewing
constraints. We present the proof by showing that the latter notion, which is
defined as a monoidal natural transformation, can be expressed in terms of
generators and relations, which correspond exactly to the defining data and
axioms of a Cardy algebra.
