MTL - After Waking up Beside the Villain - Chapter 141 Ogami Mamoru No.

In the northern part of the world, a long-standing battle between various races and the demon race has finally reached its end. The Demon Lord, a figure with black hair, red eyes, rules from her obsidian palace, having repeatedly defeated the Goddess, the strongest being in the world. However, she refrains from killing her, knowing she will only be reborn to lead another attack.As the goddess kneels before her, badly injured and helpless, the sounds of explosions echo outside, signaling the imminent victory of the alliance. Despite her immense power, the demon lord acknowledges the demon's overall weakness compared to humans and the Alliance. The development of fighting energy and mana has allowed ordinary humans to fight demons, leading to the demon army's defeat.Aware of the Alliance's intent to enslave the abyssal demon, the Demon Lord decides to cast a forbidden spell that will cost her life. As the Alliance forces storm the palace, they hesitate upon sensing the spell's energy. The Demon Lord vows to resist and be reborn to save her people.Meanwhile, the goddess reflects on the demon lord's past treatment of her and acknowledges her respect and dedication to her people. As the demon lord prepares to cast the spell, the goddess asks if she can abandon her plan and live freely. However, demon lords are duty-bound to restore the demon race's glory and protect her people.Understanding the demon lord's resolve, the goddess readies her sword, intending to clash with the demo lord's forbidden spell. The resulting explosion creates a mushroom cloud, marking the end of the conflict and the start of a new era. The Demon Lord and the Goddess become historical figures, their stories occasionally told.

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

This is the era where people prioritize science and Martial Dao. After the great disaster, the human race discovered the Ancient Zenith civilization. They entered the Age of Great Cultivation and began their journey to colonize the Kunlun Realm!