When morning comes, head downstairs and use the telephone to call your mother. Of course she's an annoying woman and will refuse your plead.
After getting refused by your heartless mother, head up to the second floor and to the west wing. Enter the southeastern door on that wing.
Examine the trash bin inside the room to find a crumpled paper with another riddle written on it.
Leave the nursery and head to the eastern wing on the second floor, then enter your uncle's office and interact with the lampshade and turn it on.
Then turn off the light switch beside the door and make your way to the lampshade to find the next key.
Leave your uncle's office and head back to the western wing on the second floor once again. Use the key that you found on the northeastern door on the west wing.
Examine the nightstand on the left side of the bed to find another piece of paper with a riddle on it. Now go down to the first floor and out the garden.
In the garden to the upper right you'll find a well. Interact with it to find another key, but you will unfortunately fall down the bottom of it.
At the bottom of the well, interact with the wall on the north side to trigger a cutscene and open a hole in the well wall.
Proceed inside the insanely long maze inside the well. The monster will be right behind you the entire time, but for some reason it's a lot slower in this area than in the house so just keep going and you'll be fine.
Shinji will come to your rescue and he will also ask you to stay in his house for the moment. In his house, interact with his bed to go to sleep.
After waking up and finding yourself back in the haunted house. Go down to the first floor and head straight for the door. The monster will block your passage and you'll have to hide.
Turn right towards the first floor's eastern wing, then enter the only door on the southern wall in that wing.
Inside you'll find yourself in a tatami room. Turn right and hide inside the small sliding wall to stay safe until morning.