MTL - A Blessed Daughter - Chapter 33 very clear

Solver Keter, one of the Five Lunatics of Lawless City, regresses to when he was the illegitimate son of a doomed archery family.“If I regressed and couldn’t even save my family, I might as well go kill myself.”For my family? No, for my freedom!

A teenager who unexpectedly gets transported to the modern world from ‘the world of the immortals’ . He finds himself in the body of an ordinary guy. He wants to go back to his world and for that, he will have to practice to get stronger and investigate the reason why and how he crossed through to this world.

- Description from Novelupdates

She was reborn in the 1970s, when there were no mobile phones or TVs, people lived in poverty and marriages were arranged by families. He, the wealthy and powerful head of the regiment, who governed the local army, helped her join the army so that her family would no longer be bullied and could live a good life. And Suddenly, he proposed marraiage to her...

The only way to stop the earth’s doom.Is to seduce the girl who is the student council president.