Vainqueur the Dragon - Chapter 0: The Great Calamity

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

Playing under the plum trees and riding on bamboo, those were the days of joyful play. It was when they first met.She was not shy but innocently charming, standing before the breeze with her hair flowing, her complexion as creamy as curds.After waking up, Xu Qingfan had returned to 20 years earlier, to the year 2002.That year, the sky was very blue, the clouds were very white, and the wind was very noisy.That year, his Childhood Sweetheart hadn't gone abroad, their parents hadn't gone grey, and he hadn't the worries of being unaccomplished.That year, he was six, she was five, and they both could fully experience the climate as snowflakes blossomed.PS: This book is also titled “Help, I'm Surrounded by Childhood Sweethearts” and “I Have a Little Too Many Childhood Sweethearts.”

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

A hundred years ago, he was a genius of the Emperor's Domain who made even the God of War wary. He was unparalleled in both alchemy and martial arts. However, his friend betrayed him, leading to his untimely demise.A hundred years later, he rose from being a dandy young master, starting everything anew. From then on, the world witnessed the emergence of an extraordinary genius.“Boss is even more ferocious than a wild beast!”“Boss values friendship above all else. He is forever my best friend!”“Kevin, no matter how long it takes, I'll wait for you. I won't marry anyone else!”“Don't ever provoke that man of calamity. That guy is a beast!”“I am Kevin Anderson, who dares to defy me?!”