Toaru Majutsu no Index - Volume 16, Chapter 1: From Peace to Ruin on the Proceeding Path. Battle_of_Collapse.

“Kill them all - every last member of House Grim must die tonight!”That was the last thing Renard heard before his world turned to ash. One night was all it took for him to lose everything - his family slaughtered, his home burned to ashes, all because the other Great Houses branded them traitors.They thought they wiped a noble line. Instead, they created a monster.Rising from the despair of losing everything, Renard became the beast Sovereign. He embraced the darkness and rose to the position of the 7th commander of the dreaded demon army.Leading an army of Demons and monsters, he brought three legendary Heroes to their knees and crushed four Great Houses to dust. But just as revenge was within his grasp, the champion of Humanity - Klean Weaver's holy sword pierced his heart.Renard thought that was the end.But something impossible happened.He woke up in the past, in a time when his family still lived and House Grim stood strong among the Eight Great HousesA second chance!A chance to change everything.That wasn’t all.For unknown reasons, he inherited the Legacy of the Devourer, a power that lets him consume the strength of his enemies.Was it a curse? Or a blessing? He didn’t know. But for Renard, it is simply a tool to protect what's his.The Lords of the Great Houses think they're untouchable in their high castles. They have no idea what's coming.This time, the Beast of House Grim hunts first!!

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

A terrible calamity has fallen onto Zhang Fan, not only becoming one of the three survivors of Grass Temple Village, where everyone else was horribly massacred, he was also tasked to carry one of the most evil artifacts, the Sinister Bead, and taught one of the most secret teachings of the Skysong Sect, the Brahmin Wisdom. Now he cultivates in the Jadeon Sect, his knowledge and possession will draw him into a chaotic story where he will have to carry some of the greatest burdens of the Martial World.

A legendary powerhouse of his generation, tired of the bustle of the peak, returned to the ordinary city and started a new life as an ordinary teacher. He wrote the legend in the city.

Magnificent mountains and rivers, the rising powerful ones. Some ancient martial art masters stood at the peak, becoming legendary. Some financial crocodiles rose up in the minuscule places, laughing arrogantly.

However, watching the school beauties was better than fighting and killing; educating was better than fighting for fame.

- Description from Novelupdates