How to move on to the "Inside Alice's Socks" event
If you are away from Alice during the daytime and observe her behavior, she may walk out of town and sit down. her at that time, she may take off her shoes. If you stay near the sole of Alice's foot for more than 10 seconds at that time, you will get an option to enter the event.

Please note the in-game time, as Alice will sleep at night.
If Alice does not sit down easily, you can make her a little tired by playing with her, etc., to make it easier for her to sit down.