I Reincarnated into a Mermaid Legend

In her previous life, Yuan Yuehui was the Imperial Preceptor of the Tang Empire. She died unexpectedly when an explosion occurred while she was making pills. When she woke up, she discovered that she had become a little mermaid in some unknown sea?! Because she had black hair and black eyes, just like in her previous life, the blue-haired, green-eyed mermaids rejected and drove her away. Fine, drive her away. They were never cut from the same cloth anyway. Yuan Yuehui was human, not a fish! She spent ten years exploring the depths of the sea, using her past-life alchemy experience to brew countless batches of dark potions. At last, she succeeded! In the midst of a painful shedding that felt like her bones were being eaten away, her tail split apart and turned into a pair of legs! She was human again and could leave the ocean and return to shore! Before leaving, she also subdued two giant abyssal sea serpents and marked them with a spiritual seal, making them guard her home under the sea. But when Yuan Yuehui came ashore, she discovered that this world was a little different...