Which main characters in novels had led humans to discover the underground world through the system?

In a land where no magic is present. A land where the strong make the rules and the weak have to obey. A land filled with alluring treasures and beauty, yet also filled with unforeseen danger. Three years ago, Xiao Yan, who had shown talents none had seen in decades, suddenly lost everything. His powers, his reputation, and his promise to his mother. What sorcery has caused him to lose all of his powers? And why has his fiancee suddenly shown up?

Qin Tian, ​​a genius in the cultivation world who failed to become a Heavenly Emperor, ended up dying at the hands of his enemy who succeeded in becoming a Heavenly Emperor. But after his death, he was reborn in a mortal world called earth. It is a world that is advanced in technology. One day, suddenly appeared a game called (Sixteen Heavens). "Why is the name of this game the same as the name of my original world?" Qin Tian wondered in confusion when he first heard about the game. ... This novel also has a very good romance harem, soo, if you are a harem fan, I'm sure you will really like this one.

Bell Cranel was rejected by every familia he tried to join until he met Hestia. In a few, he was rejected quite violently. And in one particular instance, he was thrown out and bashed his head against a wall. Well, that's apparently where I come in. Not sure how and why I'm here. Not even sure who 'I' really am at this point since Bell's memories are definitely clearer than 'mine'... But I guess we're doing this. Hopefully I've got some useful cheats. Maybe?

# SCI-FI Su Shanshan died a violent death eight years into the apocalypse but somehow, she opened her eyes to find herself reborn. Time had turned back to the day before the apocalypse. Having the chance to start over filled her with hope. Having lived through the bloody violence of the apocalypse, she now had the skills and knowledge to survive and thrive in the end times. She would repay the man who gave his life trying to save her even though she broke his heart. The big brother whom she had reviled in her previous life. This time, she would take a chance on love. As if blessed by the heavens, she had unexpectedly been given a spatial superpower, with which she hoarded resources that would sustain her in the apocalypse. When the world changed in an instant on Doomsday, and hordes of flesh-eating zombies roamed the place, she set off on a dangerous journey to find him, determined to alter the course of events that unfolded and change what happened in the past. Characters: Su Shanshan (beautiful, cold, proficient at martial arts), Gu Jincheng (rich, brilliant, awkward in affairs of the heart)

In the endless Universe is eight primordial laws. Each of the eight laws have been fused with a supreme expert, but unbeknownst to everyone, there is a ninth law in the universe. It tears open the Primordial Chaos and is beyond reach. Di Jiu—whose name is a homophone for 'ninth'—is the ungifted son of a powerful Di family clan in the Ji Nation as he lacks martial roots. Unwilling to resign to his fate, he practices medicine, hoping to one day cure himself. One day, the king orders a massacre of the Di family, forcing Di Jiu to flee. He ends up traveling to a portal into a post-modern Earth where cultivation has been made possible with the appearance of Planet Fairy. What awaits Di Jiu in his bid to seek revenge and figure out the truth while he switches between dimensions?

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