  We construct a gauge-invariant action for open superstring field theory up to
quartic order including the Ramond sector based on the covering of the
supermoduli space of super-Riemann surfaces, following the approach presented
by Ohmori and Okawa. Since our approach is based on the covering of the
supermoduli space, the resulting action naturally has an $A_\infty$ structure.
In our construction, adding stubs to the star product can be easily
incorporated, and we explicitly construct an action for open superstring field
theory including the Ramond sector with stubs up to quartic interactions.
