Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 129 - : Tide of Corpses

Haruma Kazuki is a cursed (or maybe just deeply unfortunate) high school student whose lewd, panicked, or absurd thoughts literally manifest in reality — especially when he tries not to think about them. The more he denies or avoids feelings, the more chaotic and trope-heavy the consequences.

After spending his sixth year at Hogwarts a century ago, Harry finds himself back in the cupboard under the stairs in 1991, once again receiving his Hogwarts acceptance letter.“You’re telling me my parents were killed by a dark wizard?” Harry asked. “Who is this dark wizard? Why are you all so afraid of him that you won’t even say his name?”“It’s Vol—,” Hagrid began cautiously. “Well, we call him Voldemort, because he personally killed hundreds of people.”Harry nodded nonchalantly.“And what happened the next day?”Hagrid: “Uh?”--

A genius talisman practitioner is reborn as a seven-year-old girl! However, her innocent appearance belies her vicious personality.
In the remote countryside, the Crown Prince runs into her, beating up her enemy. She is indifferent, but it’s love at first sight for the Crown Prince!

“Not good, Your Highness the Crown Prince, Her Highness the Crown Prince Consort used an immobilization talisman on His Majesty the Emperor, and His Majesty is currently eating dirt in the main hall.”

“Isn’t that normal? Who told that dog emperor to provoke my wife? I say it’s a job well done! Pour a bucket of ice water on him to cool him down!”

- Description from Novelupdates

mc gets transmigrated to Fallout New Vegas with the merchant system. let the questionable adventure begin.