This is obviously the aftermath of a yet-unnamed harem romcom, where MC has chosen the comparatively-modestly-sized B-cup Tsundere twintail childhood friend, much to the chagrin of all the other candidates.
Desperate to overturn the reality of the situation, the losing ladies resort to the most obvious tactic: utilizing their Weapons of Mass Distraction. MC does his best to resist, demonstrating a high degree of loyalty.
Unbeknownst to them all, (including the MC,) his girlfriend, undergoing a serious bout of insecurity and possessing an understandable inferiority complex, has elected to get breast surgery, and will return at the very end of the series, sporting Q-cups.
Very bad manga tbh, doesn't have any sort of plot, those boobs are clearly oversized and no one likes NTR, this only relies on people liking oversized boobs. Very unappealing 3/10
My only complaint is it would be funnier if instead of each chapter being unconnected each one was replacing the previous one and is one cup size bigger. I would love to see how long the author could keep it up.