Is a Super Magical Weapon created 400 years ago by the Nirvit Tribe. Which has the power to turn light into dark and vice versa, Meaning that it has the ability turn people from good to evil and evil to good. However this weapon only works on those who are teetering between light and dark. This works when people are wavering in their emotions and forces people to change alignments between light and darkness.
400 years ago war was common in Earthland the Nirvit were a tribe of people who remained neutral in conflicts. To try and keep the world in peace, they constructed Nirvana to force people into stopping the wars that ravaged the world at that time. After succeeding, Nirvana became a symbol of peace and the Nirvit made it their home. However, for all the darkness that it had turned into light, Nirvana took more and more darkness upon itself. It turned its residents, the Nirvit, from light to darkness and made them fight among themselves until it was impossible to survive. This would eventually be their undoing as the Nirvit Tribe was wiped until on one survived remained Roubaul who body had perished but his spirited returned as a ghost until one Nirvana could be completely destroyed.
400 years later Nirvana was later found by the Dark Guild Oración Seis. Whose goal was to use to plunge the world into chaos.
Nirvana effects a person by turning affliction from light to dark and vice versa, meaning it can a good hearted person evil and dark hearted person good.
However Nirvana must good various stages in order to work. It's first only those who teetering between light and dark will be effected while majority will not.
If Nirvana reaches the final stage itself almost all people within range of the weapon will switch afflictions. It appears a highly powerful weapon as it wiped it's creators the Nirvit Tribe over night. It was also able to effect Naruto Uzumaki and make him attack and nearly kill Ichigo.
Sherry was effected by Nirvana around 8 years after she thought that Lyon Vastia had been killed Sawyer, blaming Gray Fullbuster who was fight along side him for not saving she attacked him. She then processed to attack the other members of Fairy Tail. Later when she sees Lyon, she passes out and Nirvana influence leaves her body returning her to normal.
Richard was effected by Nirvana around 8 years ago. During his fight with Jura Neekis he remembered his brother Wally Buchanan because Jura's bald head reminded of a potato he and his brother once split together. Unlike Sherry after Nirvana was destroyed he didn't revert back to evil and instead went peacefully for his crimes.
Kyros was effected by Nirvana during his fight with Erigor. When he tried to attack his daughter Rebecca he violently attacked him by continually punching him in the face would have killed him had Rebecca not intervened. Kyros then noted at that moment that he felt like the killer he was years ago and wondered if that Nirvana's influence.
Naruto was effected Nirvana after Ichigo failed to allow it to fire after his fight Gekko Moriah. He started to attack him because of the constant failures as well. Along with Yumichika Ayasegawa's death. Because of it he started blame Ichigo for it calling him weak.