The southwest is the heavy corner in Vastu Shastra. Its dikpala is Nirriti, associated with dissolution and disorder, and the tradition responds not by avoiding the quarter but by loading it: the ground is kept highest there, the walls thickest, the heaviest storage and the master bedroom placed in that corner, so that the mass of the building sits over the direction from which decay is expected. It is the exact structural opposite of the treatment given to the light, open, watery northeast, and the two prescriptions only make sense as a pair.
Japanese practice again reaches a comparable conclusion by another route. If the northeast is the kimon, the demon gate, the southwest is the urakimon, the back demon gate, the point directly opposite through which what entered may leave. In the twelve-branch naming of the horizon it is hitsujisaru, the sheep-monkey direction. Household siting rules treat the two diagonals as a single axis to be managed rather than as two separate problems.
The Chinese Later Heaven arrangement places the trigram Kun, the receptive earth, in the southwest, and in that scheme the quarter carries none of the menace the other two systems attach to it. Kun is the mother, patient and sustaining.
Three systems, one bearing, and three incompatible readings: the quarter to weigh down, the quarter to guard, and the quarter of the nourishing earth.