Kujibiki Tokushou: Musou Hāremu ken - Chapter 90

MC (female protagonist) dies in a plane crash and wakes up in the body of a beautiful but corrupt and lascivious prime minister in ancient times, Zhang Qinglian. As circumstances decree, he (she) cannot reveal that the original owner’s soul is gone else calamity might occur. So he (she) decides to walk a righteous path, determined to help the lovely but simple little emperor rule the country. Not backing down after facing torture, not losing courage, destroying rebellions and facing off with scheming princes.

- Description from Novelupdates

As a child with an unattainable dream, I yearned to become a Hero, but I veered off the right path. Looking back, my aspiration to save others was nothing more than a foolish dream. I now realize the magnitude of my sins and the impossibility of atoning for them.

His mother kidnapped by the Ice God Pagoda at a young age, Nian Bing grew up travelling with his father, avoiding pursuit. One fateful day, he was forever separated from both his parents and inherited two immortal treasures from them, the Ice and Snow Goddess’ Stone and the Flame God’s stone, allowing him to use ice and fire magic in harmony, a feat unheard of. Taken in by a former chef of legends, once known as the Demon Chef, he creates legendary cuisine while walking the path of vengeance!

- Description from Novelupdates

In a world teeming with Titans, Colossals, Gigantic Monsters and Kaiju's, Erian who reincarnated makes his living collecting scraps of low-grade Defective Genetic Serum, realised he transmigrated along with his system.

Follow Erian as he grows to become the strongest Disaster Grade Titan with the help of his Titan System!