Manga wo Yomeru Ore ga Sekai Saikyou ~Yometachi to Sugosu Ki mama na Seikatsu~ - Chapter 66 – Frankenstein

In the world of Norse mythology, a human boy falls in love with Waltraute, the fourth Valkyrie sister. He wishes to marry her, but Waltraute gives him an impossible challenge to deter him.

Nevertheless, the boy is determined to carry out the dangerous task and to marry Waltraute afterwards.

King Grey has unrivaled strength, wealth, and prestige in a world governed by martial ability. However, solitude lingers closely behind those with great power. Beneath the glamorous exterior of a powerful king lurks the shell of man, devoid of purpose and will. 

Reincarnated into a new world filled with magic and monsters, the king has a second chance to relive his life. Correcting the mistakes of his past will not be his only challenge, however. Underneath the peace and prosperity of the new world is an undercurrent threatening to destroy everything he has worked for, questioning his role and reason for being born again. 

Those people killed her grandmother, murdered her younger brother, trampled the people she deeply cared about, and even took her own life.

It was because she trusted her ambitious stepmother and half-sister;

because she mistakenly believed that womanly virtue is to have no talent;

because of her noble status and origin….This is what caused her death.

Buried in river water, Ouyang Nuan, gritted her teeth and spoke, “I, Ouyang Nuan was wronged in death. Even if it takes forever, I will become a devil, and in the next life, will not let you off!”

When she once again opened her eyes, Ouyang Nuan was sent back in time to when she was twelve years old. Around this age, her forehead was scarred, her brother fell into the water, and in three years she will be married…

In this life, she will try to change everything to guard and protect those she cares for from those with treacherous intentions. She will live a glorious life!

- Description from Novelupdates