After waking up in the morning Miki will remember the key she found at the well. Leave the tatami room and head for the stairs, use the key to open the door beside the stairs.
Climb down the stairs and attempt to go inside the basement. Miki will complain about it being to dark for her to proceed inside.
That's your cue to go back upstairs and examine the drawers on the left side of the door that leads to the second floor toilet. Yiou'll find a flashlight inside.
Go back to the basement now and you'll be able to enter. Head for the far right corner of the basement to the north. You'll find a red scribble on the wall, examine it.
Now go back up to the second floor and into your aunt's study room. Input the numbers that you found on the wall into the PC to find your aunt's diary.
Leave the study and head for the stairs. The doorbell will ring again, go there and open the door to have a little chat with Shinji.
At this point you'll have a choice as to either believe the monster is real or call it a delusion. Choosing to believe in the monster will make the game a little longer. If you choose to say that it's a delusion, then just head back to the computer and the game will end.
but if like me you chose to believe it's real, then head back inside the house and the phone will ring. Answer it to find that it's your crazy mother calling you.
At night head out your bedroom and towards the door that flung open on the first night. Save your game before entering.
Get away from the monster and run down to the first floor and enter the basement. Once there the final cutscene will start marking the end of your closet sleeping habits. Choosing to believe in the monster will give you the good ending, you can retry the last chapter to see the alternate bad ending.