Okay, what Ayra was saying is that...
On normal days, you can enter any building from 9:00 - 6:00 (unless it's on a day that it's closed).
When you have 4+ FP with the owner of the house, you can enter the house after 6:00 PM (it's like you have "advanced privileges")
You must have 4+ FP with the owners to go into their houses on Festival days as well, since they are all technically "closed". The only one you'd want to go in is the Clinic anyway, nobody else is in their house.
They clinic is open even on fesivals, so you can go in during buisiness hours even without 4 FP. Natalie still makes potions, sells herbs, etc. She just happens to be drunk while trying to cure you xD
I discovered them at the clinic on accident.
I went to the dojo and was owned, and woke up to ray and them.
I was all, ":'D I'M SPECIAL."
It was just a holiday. =.=