Sir, How About A Marriage? - Chapter 19

"An accident. She's pregnant. How unlucky. She got pregnant in one shot!

As his contract-marriage wife, she just wanted to fulfill the mission given by his mother—having a baby. They didn't love each other, so he always used contraception before they got laid. She had been obedient to him, only to find that he had gone too far! He actually didn't care about their child at all! She couldn't stand it anymore, so she handed him the divorce papers and left, noting: “The world is so huge that I can surely find a better man.”Looking down at her, he retorted, “Come on, your purse strings will tighten up first before you find anyone.”

While the demons were rising, mankind was about to become extinct. Six temples rose and protected the last territory of mankind.

A young boy joins the temple as a knight to save his mother. During his journey full of miracles and tricks in the world where temples and demons are antagonistic to each other, will he be able to ascend to the strongest knight and inherit the sealed divine throne?

- Description from novelupdates

Crossing to One Piece world, he became Roger’s younger brother.