As per Vastu, NE is the area that should be lighter and the SW should be heavier.
Inorder to make NE lighter in your case, Make SW heavier, by adding load to it.
Since there is a stair case in the NE direction there is more of Earth element in this zone. This zone is of water element, so possibally try to add more water element without putting load above the ground level.
Most importantly check if this NE is of the plot or the Building that you are staying in.
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