Elf Tensei Kara no Cheat Kenkoku-ki - Book 2 Epilogue 1: Oath

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

- Description from Novelupdates

In the year 2057, the world has become a corporate-run utopia for the super-rich, and a hellhole for all the rest. Catherine 'Cat' Leblanc is an orphan that is about as far from super-rich as one can be. When the Incursion alarms start blaring and the sky starts raining hungry xenos, it's just another blemish on an already piss-poor afternoon. A cyberpunk magical-girl alien-invasion LitRPG.It’s exactly as wild as it sounds.

Eira Kingston, a feared assassin, never imagined that death would lead her to transmigrate into the body of Ephyra Allen, the disgraced first daughter of the once-powerful Allen family. But what shocked her even more was the soft mechanical voice in her mind, addressing her as “master” and informing her that her soul had returned to its original body.Eira dismissed the strange voice, thinking she was having a post-death hallucination. But waking up in a hospital, with memories that weren’t hers flooding back, she was forced to confront the truth.Ephyra’s life had been nothing short of a nightmare. Despite being the legitimate daughter, she was labeled a bastard, shunned by all, and overshadowed by her scheming stepsister, who had stolen the love of her father and her betrothed. To make matters worse, the wealth and status the Allen family enjoyed were all thanks to Ephyra’s late mother, and the only reason she hadn’t been discarded entirely was due to her mother’s inheritance, locked away until she turned eighteen.But Eira wasn’t one to be defeated by circumstances. If she was going to live Ephyra’s life, she would do so on her own terms. She would destroy those who had caused Ephyra pain, claim the inheritance that was rightfully hers, and find out who was behind her own death. Because if there was one thing Eira knew how to do well, it was to survive—and make her enemies pay.However, being a high-schooler with nothing to her name wasn’t enough. As Ephyra, she’s powerless, but as an assassin, she’s lethal. Still, even that wasn't enough until she became the contracted wife of Lyle Aelion—a powerful, enigmatic figure in the business world with a secret illness. And it turns out, the only thing that can relieve him is her scent.

The young Xiao Yi bore a mysterious seal within him, yet due to his father and siblings’ injustice, he was sent to the remote Nanhuang and became a son-in-law to the Fang Family. On his wedding day, the seal inside Xiao Yi was unlocked, and from then on, he controlled the Eternal Celestial Tomb! Many of the strongest beings from all the heavens and worlds were buried within the Celestial Tomb, and Xiao Yi, who now commanded the tomb, began his life’s journey of gaining strength through grave-robbing! “You think you’re a martial arts genius? Let me dig up a Martial God’s grave and we’ll see!”“You consider yourself an alchemy expert? I’ll dig up a Medicine Saint’s grave and then we’ll talk!”“You’re the son of a divine emperor? I’ve got plenty of divine emperor graves here!”“You’re the number one scoundrel in the world? ... You win, I’m out!”