Strongest Survival by Otome Game’s Heroine (LN) - Chapter Volume 5 11: Castle of Lurking Darkness

After an unexpected accident, An Luo was reborn as the young master of a business family. Even as his grandfather’s favored grandson, he seems to only be a cannon fodder in the brothers’ struggle to seize power. However, the most frightening thing is… the strange emotions that flicker in his little brother’s eyes as he looks at him. At that moment, overwhelmed by his brother, An Luo angrily thought: Could it be that he is doomed to never escape this vicious cycle of “brotherly love”?

An Luo(frowning): After rebirth, I don’t want to be together with some strange person.

Someone(suddenly appearing in the back, smiling): What did older brother just say?

An Luo: …Nothing.

- Description from Novelupdates

A master assassin transmigrates into an interstellar era.

Our protagonist Caam is a man from Earth that was reincarnated into this world as a demon. In order to survive, he spared no effort in avoiding the sparks of battle and without noticing it, he became strong himself.

“Darling, I love you…” He was the heir to the consortium and she had just divorced. The day she was divorced, she was kidnapped and forced to be the doctor in charge of his case. To add insult to injury, this man would sleepwalk to her bed every two to three days… another headache!