Ragna the Bloodedge is a wanted criminal with an extraordinarily large bounty on his head (well in the trillions) for attempting to destroy the Novus Orbis Librarium, and is Jin and Saya's older brother. He is the main protagonist of the series and a playable character.
When he was young, Ragna lived in a church with his younger siblings Jin and Saya, and was watched over by the sister of one of the Six Heroes. At some point, Saya became very ill and Ragna decided to look after her, and in turn spending less time with his brother. Jin eventually grew jealous of Saya for being able to spend a lot of time with Ragna, and he began to hate her.
Soon after Saya became sick, the church was burnt down by Jin and Yűki Terumi, who also cut off Ragna's right arm and kidnapped Saya. At some point, Ragna was bitten by a vampire which supposedly turned his blonde hair into white. He was later found by Jubei of the Six Heroes where he proceeded to train Ragna on how to control the power of his newly acquired Azure Grimoire which replaced his lost arm and repeatedly stated that although the item was a part of him now, the power was not his to command yet. For the next few years, Jubei trained Ragna to control the power of the Azure, being periodically watched by Rachel, who requested Jubei to take care of him. During the time, he met Taokaka as a child. When his training was at last complete, Ragna had finally come to the decision to depart on his journey. But before the three would part ways, Jubei took Ragna to the burnt down church and handed Ragna two items once belonging to a hero named 'Bloodedge': his jacket and the sword - Blood-Scythe. Feeling the weight of the man that gave hope to the world and the Six Heros, Ragna finally takes off, his training now complete.
Ragna has a deep hatred for the Novus Orbis Librarium, and travels from city to city destroying their bases; due to this, he has become a world-known criminal and has a bounty on his head "large enough to buy a small country", according to Jin. Despite this, he seems to travel through cities by night without much fear of being detected or captured by the NOL or any vigilantes.
On the date 2199/12/31 AD, New's Year Eve, Ragna travels to 13th Hierarchical City of Kagutsuchi to destroy the NOL base located there. Along the way, he has a brief confrontation with his younger brother, Jin, inside the headquarters. After the fight he makes his way down to an elevator shaft that leads him straight down to the headquarters basement. There, he meets Hakumen of the Six Heroes and a lengthy battle ensues. As Ragna is about to lose, he activates his Azure Grimoire to tap into the power of the Azure and is able to defeat Hakumen.
He then arrives at the battle between Noel Vermillion and Nu-13. Right before her death blow, Ragna intervenes and saves Noel, but can't defeat Nu, either. Noel then saves Ragna from being taken by Nu, who wanted to fuse and jump into the Cauldron with him.
Rachel then appears and tells Ragna that Noel is the new "eye", who will inherit the true Azure, and that the world will change. She then departs to activate her Tsukuyomi Unit to protect Kagutsuchi from a powerful blast that came from the Nox Nyctores named Gigant: Take-Mikazuchi. Shortly after Rachel returns, Hazama appears before all three of them, and Ragna immediately recognizes him as Yűki Terumi, the one who cut his arm off and burned down the church. He and Rachel attack him, but Terumi merely rubs them off, stating that Ragna is too weak for him to fight and Rachel is the only one who can keep up with him. He then leaves the three of them.
After the incident at the Sheol Gate, Ragna lets Noel travel with him for a short time, though he tells her to leave afterwards, upsetting Noel who tells him that the next time they meet they will be enemies. He is shortly thereafter attacked by the vigilante, Carl Clover, managing to beat the boy though he is dealt a nasty blow from Nirvana. He then wakes up in the Kaka Clan village, having fallen in there and spends the next few days recovering and becoming friendly with the Kaka Clan, including Taokaka.
He leaves shortly thereafter and meets Platinum the Trinity before fighting Lambda-11 due to Kokonoe messing up the teleporting process. After fending her off, Ragna hears from Kokonoe not to fight Hazama as he can't beat him. Hearing Noel's name from Kokonoe prompts Ragna to find Rachel who tells him where to go, though reminding him that he mustn't fight Hazama. He then runs into Jin at the Librarium branch, and he manages to beat Jin. There Jin also warns Ragna not to fight Hazama, saying Ragna cannot beat him.
Nonetheless, Ragna proceeds to fight Hazama, though his Grimoire is useless as Terumi, the original creator of the Azure Grimoire, locks Ragna's. Ragna is forced to watch as Noel descends from the Cauldron as Mu-12. Just as he is about to be killed, Nu intervenes in Lambda's body and gives Ragna the Idea Engine, allowing him to bypass his Azure Grimoire's restrictions and allow access to the true Azure and defeat Terumi. He runs to Rachel to free her from a binding spell cast by the phantom, and then fights Mu. Ragna manages to wake Noel's mind by using the True Azure's power to activate the Idea Engine though in the process his left arm is destroyed. After the fight, he, Jin and Noel see that Hazama and Relius Clover are working for Saya , which is a shock to them. After they leave from Kagutsuchi, he, Jin and Noel decide to leave the city and become stronger. Kokonoe gives Ragna a new mechicanal arm using parts from Lambda's regeneration tank. Ragna leaves for Ikaruga with Taokaka, who was ordered by Jubei to go with him much to Ragna's dismay, but he caves in when he realizes Tao would follow him even if he said no. Afterwards, he and Taokaka headed for Ikaruga, as Ragna stated that there's something he needs to do there.