Sorry that they didnt felt like home.. The "private party" was a dinner with 5 the first night and 4 the 2nd.... Not 8...! And we left home a bit after midnight .. So the night was quite.
It is clearly mentioned in the appartment description that we have to share the toilet, its true that 3 more persons use it during the 3 hours of the dinner...the kitchen and living room are shared aswell... Sorry if they were to shy to go out of their bedroom... Most of the time we invite of guest for drink or dinner witout any problem, we also share dinner.... Maybe you should have choosen hotel or rent an entire appartment for your parents at their age and with a culture and language so different. I dont speack Japanese..