Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 17 - 17-20. Demon God

Amamiya Hiroto is unlucky. His life consisted of misfortune after misfortune, culminating in an unlucky death during an incident on a school boat trip, trying to save a girl he barely knew. After death, he met a god of reincarnation who requested that the hundred or so dead passengers—one of them being the girl he tried in vain to save—be reincarnated into another world.

In her previous life, she rose from a country girl to become a CEO, working diligently until she died of overwork at 38, only to find that she had been greatly betrayed by her useless husband, who even had a child outside their marriage.When she opened her eyes, she was back to being eighteen years old, facing grandparents who favored boys over girls, a father who was honest and kind but dared not resist his parents, her mother who loved them deeply but was easily bullied by others, and her brother who still loved her despite her coldness.In this life, she decided to take her family away from those greedy relatives, save her brother from a fate of disability, and stay away from her useless ex-husband.Unexpectedly, she saved an even more important person by the roadside.“Your husband is just a country bumpkin; he didn't even get into university. How could you live well with him?” her ex-husband said.One day, a Bentley stopped next to her. A driver got out and bowed to her, saying, “Madam, the Boss is waiting for you for dinner.”“I know that car! It belongs to a rich family!” someone exclaimed.“Did he just call her Madam?” another person asked....“Did you hear? He brought a country girl home?”“They say that girl is his wife. Isn't it funny?”“Madam has arrived!” said the steward.“OMG, it's the talented girl from the famous university!”“Dear lord! She is the legend of the A-shares!”“I'm just so shocked...”“Hey, guys, she is my wife,” he said.

A great demon king who came from another world to conquer Earth. To save the Earth, Li Luyou could only first take care of this great demon king… a little girl proclaiming herself Her Imperial Princess.

- Description from Novelupdates

After being imprisoned in the basement by her mother for ten years, she ended her cruel and tragic life in death when they forced her to hand over the key to the hidden treasure. Getting reborn in her teenage years, she woke up in the bed of that terrible and powerful man. This time, she must take revenge on her enemy, and now she must live.