From now on, I am the ugly duckling in the Duke's family. Volume 3

One of the most popular manhwa. 
Sylvia Atlanta continues to develop her talents and takes exams at the magical academy. However, during a mana measurement test, the girl falls under the influence of a dark and mysterious vision. It seems that only darkness awaits her ahead. And indeed, the world around Sylvia turns out to be darker than she thought. In a monster-filled forest, she encounters cultists who are hunting her brother to kill him. And in the capital of the kingdom, people are kidnapped and then sold at an illegal auction. And this shocking truth is revealed when Sylvia's beautiful sister – Eilin – goes missing…
For a wide audience.