  This is the second paper of a series of three. We construct effective
open-closed superstring couplings by classically integrating out massive fields
from open superstring field theories coupled to an elementary gauge invariant
tadpole proportional to an on-shell closed string state in both large and small
Hilbert spaces, in the NS sector. This source term is well known in the WZW
formulation and by explicitly performing a novel large Hilbert space
perturbation theory we are able to characterize the first orders of the vacuum
shift solution, its obstructions and the non-trivial open-closed effective
couplings in closed form. With the aim of getting all order results, we also
construct a new observable in the $A_\infty$ theory in the small Hilbert space
which correctly provides a gauge invariant coupling to physical closed strings
and which descends from the WZW open-closed coupling upon partial gauge fixing
and field redefinition. Armed with this new $A_\infty$ observable we use tensor
co-algebra techniques to efficiently package the whole perturbation theory
necessary for computing the effective action and we give all order results for
the open-closed effective couplings in the small Hilbert space.
