Multicrossover: I Took Utaha's Virginity At The Beginning! - Chapter 31 - 30: From Defense to Offense – Making It Public

Her sister steal her lover

She thought it was a dream

after rolling and waking

Nightmare Reality

Her loved ones, her love, her life

They were all trapped in that big fire

burned to ashes

A young boy named Chen Zong got lucky and found a mysterious Sword Seal. With the help of it, he rose to be a God in Sword who defeated innumerable top talents in all universes from a remote borderland.

- Description from Novelupdates

Haruto Hayase was a normal high school boy in his third year, living a quiet life until his younger sister, Haruka Hayase, joined the same school. Haruka’s beauty and charm made her the center of attention, quickly becoming the school’s prima donna. But when a notorious gang leader set his sights on her, he did everything in his power to protect her—only to fail tragically. Haruka was brutally assaulted and tortured, and Haruto himself suffered an agonizing death. However, in a twist of fate, Haruto is given a second chance, waking up a year before the events that shattered his life. Armed with the mysterious ‘Debauchery System Slave’, he vows to exact revenge on those responsible. This time, he will use his newfound powers of the system and charm to seduce the loved ones of his enemies. From their mothers, sisters, and lovers to their closest friends, Haruto will make them his. His enemies will suffer as he steals what they hold dearest, ensuring their downfall in the most devastating way possible.

“The war is finally over?! Then, what am I going to do with my life?” Caedrel, a man who had spent his entire life fighting, had no idea what to do next. Fortunately, he was offered to become a teacher in the greatest academy in the world. However, he wouldn’t be a normal teacher but a spy for his country’s Emperor! Doesn’t sound too bad, right? Well, it would have been great, that is…until he learned that his class was for the most talented(weird) students in the entire world.