Lambskin Parchments

The Lambskin Parchments (羊皮紙) are a set of occult parchments, found by Accelerator in Russia during World War III and instrumental to Fiamma of the Right's plans. They would also prove instrumental in healing Last Order and introduce Accelerator to the magic side of the world.

Principles
It consists of a set of dozen sheets of parchment with eerie spells and magic circles written on them in old ink, with the words written in, but amended with small notes in at intervals. The contents include what to replace and with what in order to activate a Roman Catholic spell under Russian Orthodox standards.

The parchments contain information concerning archangels other than Michael, those associated with the other members of God's Right Seat, and their respective symbols. This information was necessary for Fiamma to make up for the gaps in the knowledge held within Index's grimoires, which were lacking deeper esoteric knowledge regarding the angels and God's Right Seat. It includes the Russian Orthodox Church's top secret inferences into the spells of the archangels, and unconfirmed information gathered from across Russia by the church, apparently incomplete.

World War III Arc
In their initial appearance, the parchments were contained in a briefcase handcuffed to a Russian soldier, present on the same Russian military convoy train which Accelerator and Last Order were hiding in, but Powered Suits from Academy City's forces attacked the train, looking for the briefcase. They managed to cut the handcuff chain, but Accelerator, thinking Academy City was after him, attacked and defeated them. The parchments were found by Accelerator, who decided to keep them, thinking they were related to the "different set of laws" Aiwass told him about and that his best bet would be to get information out of the people that these papers were supposed to be delivered to. Accelerator also felt an odd sense of pressure from them, the same way he feels around "Unabara Mitsuki".

Upon arrival at his destination, a destroyed Russian airbase, Accelerator deduced that the dstruction was the work of an underground organization from the Dark Side of Academy City and concluded that he should look into the organization that infiltrated Russia to get his answers. Before he could do that, he was attacked by Vodyanoy and twenty other magicians. Defeating them and realizing he fought an enemy using vectors and laws unknown to him (and thus might be connected to the parchments), he considered questioning them, but before he could, he was attacked by Misaka Worst.

After fighting him a second time, Kamijou Touma left Accelerator with a note informing him to look for "Index Librorum Prohibitorum" to inquire about the lambskin. Later, after reaching the Elizalina Alliance and examining the parchments, Accelerator could tell that it was some kind of manual trying to illustrate a story, but was struggling to figure it out, until a bodyguard of Elizalina told him she could decipher it for him. When he met her, she confirmed that she could decipher it, but that it would take time. Accelerator however just needed to know that the parchments could be deciphered, and asked Elizalina to focus only on healing Takitsubo.

The lambskin was subsequently revealed to be the last piece for Fiamma of the Right to fill the gap between Index's magical knowledge in order to reach his goal, with Archangel Gabriel sent retrieve it. Although the parchments remained in Accelerator's pocket during their confrontation, Gabriel was able to retrieve the magical knowledge from them through its senses and relay it to Fiamma via their link.

Accelerator would later make use of parchments together with values obtained from his encounter with Aiwass in order to acquire the parameters necessary for him to heal Last Order.

After the battle on the Star of Bethlehem, when confronting Fiamma personally, Aleister Crowley revealed that although the parchments were incomplete, it would have been a problem if they were analyzed by an anti-magicial organization such as the Anglican Church, hence why he had sent out a unit to retrieve them.

Design Evolution
Since the parchments contained a song in the form of a magical aria, Haimura Kiyotaka designed the parchments to resemble a musical score and musical notes. The version seen on the back cover is the revised version.