Plundering Worlds: I Have a Shotgun in a Fantasy World - Chapter 42: Three Seconds

The Republic of San Magnolia.

When her father passed away, her mother married into a large family. She thought it'll be a new beginning of her life, but it only brought her an substitute marriage to a disabled husband her step-sister didn't want.On the second day of their marriage, the noble and aloof man said indifferently, “Divorce or live as a widow, choose one.”She pulled off his suit pants and touched his firm and sexy thigh, “I choose the third option!”Latter, she used her medical skills to healing and saving people, including her disabled husband, who turned out to be a hidden billionaire!Nobles and celebrities sought medical advice, flocking to her like ducks.Those who humiliated her regretted it deeply, begging for mercy on their knees.The billionaire smiled proudly, “My wife is a treasure, only her husband knows it!”She rubbed her waist and gritted her teeth, “Didn't you say that you wanted a divorce and warned me to stay away from you?”

Lyle Walt is a young noble boy and heir looking forward to the day he can inherit his family’s territory. Except around when he was 10 year old, his parents started neglecting him more and more in favour of his little sister, Celes.
On his fifteenth birthday, he is challenged to a duel by his sister to see who will inherit the household and horribly loses, being cast out of his family. Afterwards, he gets treated by the family groundskeepers and receives the family heirloom Gem from him that Lyle’s grandfather had entrusted to him. From there, he begins an aimless journey with his childhood friend and former fiancée, Novem, and the Gem-turned-Jewel that houses the memories, personalities, and Skills of seven of his ancestors.

This stands at the forefront of strategy guides to Life (a shitty video game)!