Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 17 - : The Golden House Conceals the Beauty

I do not own this imageHe was a swordsman beyond compare—cold, calculating, and relentless. A man who chased power not for glory, but to break the fate forced upon him. Betrayed in his final battle, he died with his blade in hand... only to awaken in a world not his own.Now reborn in the world of High School DxD, Nero carries with him a mysterious System that allows him to defy logic:— Steal and evolve Sacred Gears— Accept world-altering quests— Access a store that sells power itself— And shatter the limits of every universe he entersWith the power of his Void-Forged Blade and a will forged in war, Nero walks among Devils, Angels, and Fallen—but he kneels to none.As he joins Kuoh Academy, crosses paths with Rias Gremory and her peerage, and uncovers the secrets of the multiverse, one thing becomes clear:This world, and every world after it, will tremble beneath his blade.

Asura – proud, warlike, cruel, heartless.

A young adult with a mysterious background follows his father’s prophecy and enters the world of «Rebirth», somehow managing to inherit the Xuanyuan Sword, and also unexpectedly obtaining the hidden class Asura.

Following the tracks of both virtual and reality he gradually discovers a secret hidden for the past billion years.

Asura, the class that used to shake the lands has now completely disappeared. He must now go on a journey to find the true meaning of Asura—until the day he transforms and becomes one with Asura.

- Description from Novelupdates

He, since childhood, had followed the Foreigner to practice the Defying Heaven Art, entering the most secretive special forces and becoming a fearsome assassin that made others tremble at the mere mention of his name. After a single failure, he took early retirement, but he ended up as the personal bodyguard for a rich heiress, a school beauty. Accidentally provoking some mysterious Cultivators, he gradually unveiled a hidden world of Cultivation beyond the mortal realm...

The game spoilers turned out to be fake. The characters I gathered thinking they were heroes are actually all villains. In other words, I accidentally created a villainous organization.