Every time I tried to use the onsen for 5 nights in a row children were in the onsen talking, running around, splashing other patrons, nobody said or did anything including the parent(s) but it totally ruined my experience and is a pretty fundamental violation of onsen etiquette. Otherwise typical / serviceable 3 star experience, not the nicest part of Sapporo to be staying in, I won't be coming back to this particular establishment.