Main theme: Some pleasant Mixolydian to start.
Summer house: Town theme vibes. Pretty effective!
Cake!: Bouncy and jolly. Love the percussion choices.
Nikumi: I love this lil music box theme.
Family: I love this vibe a lot. Great bass.
Water Game: I love this bouncy track. Very cute.
Nap: Nice melody here!
Shack: Ooh its getting scary. I like the heartbeat-like ambience.
Iron: This caught me off guard in a good way. Definitely gives me the horror visual novel scene vibes.
Nerve: This is so tough. Love the drums.
Together: More heartbeat with a cool subby sound. I like how the main theme is poking out from the creepy atmosphere.
Slumber: Ooh, love the parts after the halfway mark, beautiful but haunting conclusion.
The tracks all matched the story on your itch page p well. Nice work!