Transmigrate inside a Web Novel as a Side Character. - Chapter 14 - Reunion.

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- Description from Novelupdates

On the wedding night, when the bride hung herself, the handsome husband was sickly, the concubine was glaring like a tiger to see what her best next move would be. Shu Huan who time-travelled to the ancient times encountered such a mess.

I finally managed to kill the demon lord.