I Have Unparalleled Comprehension - Chapter 959 - : Danger! Use Fusion Technique!_2

Reborn into the world of Yugioh, it's natural if my goal is to become the best duelist!

Elena, who spent her entire life as a cold-blooded female knight to avenge her family, ended up dying without claiming her revenge. When she opened her eyes she found that she went back into the past. By day she was a lady in a dress, and at night she carried a sword to change history and prevent her family’s destruction.

The two faced number one female spy transmigrates to a different world and becomes an outrageous idiot girl. When she woke up, what she had to face was consecutive blows of the decline of her family clan, her crippled martial skills, and her disfiguration. To protect her family, she must obtain the treasured book, obtain outstanding achievements, summon a dark beast army. Wait and see how in this unfamiliar, dark magical continent, she dies and becomes a demon then steps up to the top, making all of the formidable people in the world bow down to her in respect.

- Description from Novelupdates

On the surface, he is the aloof and standoffish patriot whose sole purpose is to serve the nation. On the darker side, he is an invincible, powerful and mysterious man.