Mysterious Encounter with Little Octopuses

In a seaside town lives a girl named Miyuki. One morning, she wakes up to find little octopuses clinging to her head. Surprised yet charmed by their cute eyes, she smiles. These are messengers from sea spirits, inviting her on an adventure to find a lost treasure. With the octopuses, Miyuki sets off to the unknown underwater world. Amid the echoing waves, what secrets await?