Lidvia Lorenzetti

Ridovia Lorenzetti (リドヴィア＝ロレンツェッティ) is a radical among the Roman Catholics, also known as Mardi Gras (告解の火曜 (マルディグラ) ). She is known for evangelizing to people that the Church rejected, and has invited converts to further carry out her evangelism.

Background
She is a Roman Catholic born in the Vatican. She is in a very high position, but never tried to aim higher. Instead, she finds spreading the gospel to the world much more meaningful. She is a person who’ll do anything to spread the Word. As a reward, the Pope himself specially gave her a platinum staff that is decorated with silk, but she immediately sold it without thinking to finance her travels. Those that were saved by Lidvia, and who want to save even more people, are geniuses who had never seen the light of day, and most of them were people like criminals and cult believers. Lidvia’s talent is in finding these talents that will normally be executed.

Not only does she have the ability to find hidden talent, she’s also able to control and manage problematic people.

Even if it’s the Roman Catholics, who’ll kill any sinner that they meet and burn any non-believer, they can’t formally attack anyone who’s properly recognised as converted. To the higher-ups who hate these problematic people, they view Lidvia as a thorn in their side. And to people like the Archbishop Laura, she’s a formidable opponent.

Her nickname is 'Mardi Gras', which came from her joy of tackling obstacles that appear in her goals.

Daihasei Festival Arc
During the Daihasei festival in Volumes 9 and 10, she is behind the plan to set up the "Croce di Pietro" in Academy City that would forcibly convert its residents to become members of the Roman Catholic Church. She's also seen to be a magic user, as she was the one that activated the Croce di Pietro and is capable of using levitating spells.

After the events of Volume 9 and 10, she was captured by the Anglican Church and locked up in the London Clock Tower. In Volume 14 she (next to Biagio Busoni) accepted a deal to give what information she had on the God's Right Seat to the Anglican Church, in exchange for Oriana - who was also a prisoner at the time - to be released so she can help people that was suffering from the worldwide destabilization in political relations between various factions that arose from Vento of the Front's attack on Academy City.

In the second side story volume she encounters Kamijou Touya and tries to help him with his son's curse of misfortune, she is touched by Touya's sincere feelings to help his son and even says that they may have to rethink their original plan to take over Academy city. This likely occurs before the Daihasei Festival Arc.

Document of Constantine Arc
It is not in Ridovia's knowledge that Oriana Thomson, who had also been captured and locked up in the Tower of London, has already negotiated with the Anglican Church to set her free in order to carry out Ridovia's dream of saving the weak who have been under the heels of the recent terrible events.

Ridovia, the evangelist, is locked up in the Tower alongside Biagio Busoni, the elitist, and are visited by Stiyl Magnus and Agnese Sanctis for interrogation. After Biagio shows his defiance to Stiyl, and Stiyl shows his arrogance to his regarding the many ways his order can acquire information from them without having them alive, Ridovia speaks. She tells Stiyl that they too do not care for trivial things such as that as well, but asks what is happening outside. To which Stiyl says that she can make a guess on what was happening outside. Ridovia's expression faltered, as she cared for the weak as there were the ones Ridovia reached out to. However, Biagio can only give a harrumph at the situation. Ridovia then says something which shocks and then irritates Biagio, have everyone in the tower released in exchange for what she knows. Stiyl does not yield, and in response to this, Ridovia with simple chanting has the the Roman Catholic Church cross Agnese Sanctis has in her person to allow her to escape from her bonds. With a broken metal of her shackles Ridovia did threaten Stiyl with it, and in turn, he threatened her with his rune card. Agnese having recovered from the shock, took her weapon with her, the Lotus Wand, but Stiyl signed her not to interfere. He asks her if she though that he would allow her to take his life so easily, and Ridovia responds that she has no choice so long as he does not yield. But Stiyl remains firm in not having Ridovia get her way, and here tells her that Oriana has already negotiated with the Anglican Church and that their minds have been preoccupied with the same thoughts, to help the weak in the dark days ahead. Hearing this, Ridovia lays down her attack. Sitting down, she now confides to them the secret of the God's Right Seat.

Regarding them, Ridovia says that they are a group working to obtain victory over original sin, surprising both Agnese and Stiyl. As Ridovia mentions that there is someone who does not have the original, Agnese asks who it is, to which Stiyl glares as a response. It is revealed to be the Holy Virgin Mary. Agnese witnesses Ridovia's explanation on what she deems is God's Right Seat's true goals, which is to completely remove their original sin in order to attain some grand goal.

After Stiyl and Agnese returns from brief sojourn, Ridovia says that the God's Right Seat's goal is to attain the right seat of God, a position that was once of Lucifer before his fall, a position that was equal to God. Ridovia states that God's Right Seat, once attaining the position on being the right side of God they will be able to use that power to evolve into an existence different again from an angel, which is the La Persona Superiore a Dio. This makes both Stiyl and Agnese frown at the thought.

Lance of Gungnir Arc
In the final recreation of the world by Othinus created specifically to break Touma's spirit, known as the Version_Omega world in-text, where several characters from the original world have been "saved" or have not experienced great tragedy, people from the magic side like nuns are allowed to enter Academy City, and seemingly have no complex against science. Orsola Aquinas, Angelene, Lucia, and Ridovia are first sighted by Touma near a hot-dog truck. Angelene is eager for the expensive hot-dogs, but Lucia ever the prude tells her that Angelene is both being gluttonous and greedy, and that a nun must not eating something like that. She then turns to Ridovia and asks her to say something as well. She however, states that Orsola has already started eating one. Touma later buys a hot-dog from the same truck, apparently serving as a last meal before deciding to kill himself.

Toaru Majutsu no Index Light Novel Volume SS2
Ridovia is not fond of Balbina leaving from sermons and in one of those days in Italy where she had come to scold her, she came upon Kamijou Touya, unbeknowngst to her the father of Kamijou Touma her later foe, who would trouble her in later day. Many times did they meet, and many times did they separate paths. Though at last at their fifth meeting Ridovia finally confronts him of their meeting. Touya tells Ridovia that he is not looking for mere souvenirs but that of good luck charms as is the reason why he keeps trying to find Balbina. Here, Touya talks to Ridovia about his son's misfortune lamenting on how there is none who can cure of him from it, and ever the listener of the plights of the weary and downtrodden, as well as intrigued of Touma's unsolvability of Touma's misfortune, has Balbina give Touya a magic good luck charm that's undetectable by other magicians unless it is used actively for a spell.

After forcing a Bible into Touya's pockets, Ridovia becomes elated, and in her spell, runs towards Oriana, knocking her down. Ridovia had come to the conclusion that Japan was an enemy of society for having Academy City, but after meeting with Touya who cared so much for his child, enlightened her in a way, and deems that to conquer Academy City they must make a much more gentler and more peaceful one. Oriana is confounded by Ridovia's joy until Balbina explained to her what has transpired. And though Oriana is annoyed by her mood, she could not dwell in it long for Ridovia's body could not hold back her elation when she fell once again.

Design evolution
Similar to the theme that Haimura wanted to present in the series, like Sherry Cromwell. Ridovia was designed not to look like a typical moe character that is apparent in the rest of the girl characters.

Quotes

 * (To Touya, from Volume SS2): "Wonderful!! Such wonderful impossibility! Such wonderful irrationality!! The more difficult the difficulty, the more I want to solve it!! Heh heh heh. So you want to get rid of the misfortune surrounding your son? That speeds things up. Balbina! Magical Plant Master Balbinaaa!!"
 * (To Oriana, from Volume SS2) "T-today!! Today is such a wonderful day!! I may have been mistaken about the Japanese! I had thought they were the enemies of society for having something so uncivilized as Academy City, so I never would have thought there was a father there who cared so much for his child!! We may have to alter our plan for capturing Academy City to a gentler and more peaceful one!!"