Resurfacing, Angel tried to find some trace of the island from the angle at which she had entered the water. But apart from Ariel cautiously approaching and the Red Haired Woman slowly advancing under Helene's control, there was still nothing around her but persistent fog and a sea as calm as a mirror.
Calm... as a mirror?
Angel caught a flash of inspiration. As if eliminating an incorrect answer, she first dove beneath the surface and surveyed the surrounding water with eyes protected by an extra layer of sclera. As expected, she found only a lifeless ocean, without even fish or coral.
Then she returned to the surface, and her figure flickered, appearing beside a glass window near the stern.
This was not Mirror Substitution, but a more advanced way of using the Mirror World.
In that brief journey of barely twenty meters from the water to the deck, Angel had already discovered what was wrong with this entire stretch of sea:
Below the surface, no Mirror World space existed.
This was the crucial detail she had completely missed yesterday while using the Magic Mirror to observe conditions inside the fog.
No wonder Wensa said the time, place, and technique were all indispensable... If a Demoness searching for the Fountain of Youth was too cautious to enter these waters and only investigated from outside, she would never discover what was unusual about them...
As Angel pondered, her eyes gradually brightened.
She now knew the crux of the problem:
The island containing the Fountain of Youth was hidden inside a Special Mirror World. That space could only be entered through a particular method, rather than accessed at will like the ordinary Mirror Tunnels through which Demonesses of Despair freely traveled.
Once she understood this, all Angel had to do was find