深海の誓い~その瞳、星の彼方に~

Siren, a saint, flees into the deep sea to escape sacrifice and is saved by the sea god Leviathan. They uncover the church's lies and fall in love. When Leviathan dies protecting her, Siren becomes the Queen of the Abyss and resurrects him. Later, they discover a cosmic eye awakening, hinting at greater danger.