Rebirth : The Alchemist's Path - Chapter 18: The Beast Capture Challenge

When encountering demons, a young man with two horns on his head, red hair reaching his waist, and an extremely handsome appearance leads the demons to the front.

Youdou: Actually, I really don’t want to be a master of monsters. This profession is completely useless. My ideal is to become a magic stick…, bah, it’s to become a great onmyoji.

All the monsters: My lord, wake up, you are the leader of the monsters yourself!

- Description from novelbuddy

Ruins stretched across the landscape in the apocalypse after the nuclear war.

She was once an heiress, but later her family went bankrupt, and her fiancé betrayed her. Besides, she had to bear the expensive medical expenses of her brother. Therefore, to regain everything, she decidedly married her ex's cousin in a deal. Initially, he was very aloof and didn't care about women at all, but he gradually fell in love with her, protecting her and supporting her...

There is a very strange restaurant in the City of Sin.