the area in the picture can be accessed from the abandoned sea!
other new areas i've found:
- a mansion accessible from the area where you get the monokeros effect. there's a cupcake blocking the path, you can get rid of it using the minus screwdriver. from the mansion you can access two small areas, one has a waking up event (not sure if there's any event in the the other one)
- a rooftop area in the apartments, with an event similar to the witch's flight in yume nikki
these were all i could find, don't know if there's anything else.