One Piece : Start As Celestial Dragon And Take Down Hancock - Chapter 50: The Future Underground Queen, Stussy (R-18)

500 years ago, Chen Xi was devoured by a crack in the void and was transported into a cultivation world.

500 years later, he returned back to Earth after enduring through several hardships and discovered that only 5 years had gone by.

…

In the courtyard, beauty at the side, a candle flame wavering.

A gush of clear wind, half a full moon, the peach tree remains unchanging.

…

Wait, whose kid is this?! Why is she calling me papa? Gazing at the little girl in front of him with skin as pale as jade, Chen Xi froze.

…

　
Returning home from cultivation, starting as a stay-at-home dad.

In this life, not fighting to be a king nor claiming to be a tyrant, only praying to peacefully be a wife-pampering mad devil and a child-protecting daddy!

- Description from Novelupdates

[Trigger Warning: This dark fantasy romance contains mature themes.]---BLURB:IN A WOLD OF FORBIDDEN LOVE AND HIDDEN TRUTHS, ONE WOMAN'S DESTINY WILL CHANGE EVERYTHING.Ovelia’s life is shattered when she is sacrificed by her family to secure peace between humans and werewolves. Bound to Ace, the future Alpha King, she enters a marriage built on duty, not love. But when Ace’s wolf chooses her as his mate, their fates become intertwined in ways neither could have predicted.As Ovelia navigates the treacherous world of werewolf royalty, she faces betrayal, kidnapping, and the lingering shadow of Ace’s past love. But the greatest danger lies within herself—a secret heritage that could destroy the fragile alliance between werewolves, witches, and elves. When Ovelia’s true identity is revealed, she must flee for her life, only to discover she carries a new hope for the future.With war looming and enemies closing in, Ovelia and Ace must confront their pasts and fight for a love that could unite their fractured world—or tear it apart forever.---

Aliandra Amariel loved magic, dedicating her academic years to the study of runes and spells, pushing the boundaries of mana's infinite possibilities. Like most Fae, her destiny seemed clear until that fateful day of her Class Trial, when the Blind Lich unleashed an undead apocalypse on her home, the fabled underground city of Dal’mohra, and triggered The Breaking – a cataclysm that forever reshaped the world. Saved by her mother’s legendary time-stasis spell, Ali wakes thousands of years into a dark future. Everything she knew and loved is gone, buried under a mountain, transformed into a twisted dungeon by the malevolent will of the Lich. Now, Ali must confront her deepest fears, mastering the arts of battling monsters and braving a town riddled with corruption. As the Lich's grand design shadows her every move, she scrambles to forge new friendships and unearth ancient knowledge in her fight for survival. Why must she struggle? All she had ever wanted was to curl up in a comfy chair with a few thousand good books. But the immortal Lich is drawn to her unique magic, ever hungry for more power to fuel his cold-hearted ambitions. How will she survive the giant target painted on her back as her advancement slowly reveals the horrifying truth of the Class she chose to save herself? Will she falter, forced into the eternal servitude of undeath, or will she rise against all odds and cast him down, ridding the world of his evil?

There are 5 books on the 6 sworn brothers in a serial called streamer (流光系列). ‘They are rich, handsome and powerful. These book are on various types of love as well as on the bond and mateship between the brothers. Book on youngest 6th brother.

Chen Yu Bai (3rd brother) & An Xiao Yi – Chen Yu Bai is a sharp, domineering & cool man whereas An Xiao Yi is a foolish, childish & innocent girl. He is her boss & she is his secretary. He bullies her yet at the same time will not hestitate to protect & shelter her. Thus, she can always rely on him. Their relationship is a funny one on how opposite attracts.

Li Wei Ran (5th brother) & Qin Sang – Li Wei Ran and his cousin Qin Song fell in long with Sang Sang who is An Xiao Yi’s best friend. Sang Sang sees Li Wei Ran as a good man. He is polite, patient and passionate whereas she is independent, intelligent and interesting. They are a perfect pair but she is afraid to love so he has to work hard to convince her he is worthy of her love..

Short sequel on their children.