W 43A is a prototypical "water fountain", which hosts a highly-collimated molecular jet (>100 km/s) from a system of a dying star and is traced by water maser emission. Here we present our latest exploration for the central stellar system of W 43A through our ALMA observations. The maps of 1.3 mm continuum and SiO v=1 J=5->4 maser emission suggest that the size of the central stellar system, which may be in a common-envelope evolution of a binary, should be within 20 au. The maps of CO J=2->1 and SiO v=0 J=5->4 emission imply that the collimated jet should have precession so as to eject gas blobs alternating their red-shifted and blue-shifted components in every 5--7 years. These information will shed light on the mechanism of launching a jet from a dying star and the evolution of a binary system, which is performing massive stellar mass loss (in an order of 10^-3 M_sun/yr), forming a planetary nebula (within 100--1000 yr) with a complicated morphology, and likely going to a type-Ia supernova explosion.