——Deep, deep at the bottom of the sea.

In a world where even sunlight cannot reach, there exists another kingdom unknown to mankind.

With coral for walls, pearls lighting the streets, and jellyfish drifting like stars in the night sky, it is a paradise for merfolk—the Kingdom of Aquaria.

Ruled by the Aquamarine royal family, who carry the blood of the Sea God, the kingdom has built long-lasting prosperity through ocean current magic, healing arts, and the trade of pearls and coral.

The sea was calm, contracts were honored, and everyone believed the same peace would continue tomorrow.

...But that peace was quietly coming to an end.

Starting one day, the magic ores supporting the kingdom began to vanish one after another.

The currents grew turbulent, ancient monsters woke in the deep, and eerie singing began to echo from forbidden zones where no one dared tread.

Ancient documents passed down through the royal family state:

'When the Legacy of the Sea God awakens, the azure sea shall be stained with both blessing and calamity.'

It was no myth.

A final "wish" left by the Sea God in the distant past.

A secret known only to the royal family.

And the existence of a certain merfolk clan erased from history.

All the truths were slowly beginning to float up from the seabed.

Meanwhile, among humans, rumors have been passed down since olden times.

"On moonless nights, do not let the sea call to you."

"Those who follow that singing voice will never return as humans."

"Even if they do return, their eyes will already be the color of the sea."

Is it just a folktale?

Or is it a "spirit-away" that the sea has secretly continued?

No one knows the answer.

A mermaid longing for the sea above.

A merchant who values profit.

An inspector who believes only in contracts.

A sea witch who whispers that every wish has a price.

Their respective feelings will eventually converge into a single destiny.

This is a story revolving around the truth of an undersea kingdom that no one knows.

When the final wish left by the Sea God is revealed, the world will surely never be the same again.