Downward!

You dive down deeper under the water, and follow her down into a secret tunnel you would of never notice on your own. The tunnel turns and you follow her back up to the surface and you both break the surface of the water and find yourself in a small cavern. She slides out of water into a magical circle that glows white and her tail splits into legs and she shifts into a winged demoness.

You follow her, sliding out of the water into the circle. It glows white as magic flows through you. Wait, something has gone wrong?!

Your arms pull tightly to your side and start to fuse into your body. Little nipples form in pairs, all the way down your stomach, and along the bottom of your mermaid tail. The flesh under them swells and pushes out, as dozens of tits start to form.

The slightest pressure of your new tits touching the ground causes them to leak milk. You shiver lightly as you turn into some kind of multi tit slug girl. You squirm lightly on the ground as you look to the demoness for help.

She smiles as she lifts a hand and cups your face. "Come with me."