To an outsider passing by this apartment would be no different from the vast array that make-up the apt complex. Even if one were to place their ear on the front door absolutely no noise would emanate from the sound-proof walls, one would hear a pin dropping next to them than what was going on behind closed doors.
But, if a stranger were to slide open the unlocked doors (As is Japanese custom to never lock one's doors if they aren't hiding anything) their eyes would feast upon a scene straight out of the most perverted of "adult" films.
A young boy completely smothered by 3 gorgeous women, their clothes strewn across the entire apartment and the sounds of bare and wet flesh slapping generously alongside the sounds of licks and screams.