I'm gonna put in some guide for y'all. If you are stuck at finding the cave, then first touch everything inside the house, there are 5 notes that your old man left. Then go to the clock in your bedroom, then put the clock' hand point to the symbols written in the notes. After that you get the clock key. Go to Ivy's room, there's a hatch on the roof which requires the clock key to open, open it and take the ancient map along with the pipe. The pipe is an artifact which can be bind to increase EXP gained. As for the map, it helps open a new location called "Meraz' tomb" or something like that. That's where Scarlet's dagger is