After dying in another time-line, Ragna the Bloodedge seeks to continue his quest. He fights with his brother, Jin Kisaragi, and meets Noel Vermillion, who has strange memories of him.

Ragna beats Hakumen, one of the Six Heroes, and is next faced with Nu-13. Noel, the true successor to the Azure, saves his life and kills Nu.

As Ragna recovers from his wounds, Rachel meets with three mysterious beings and Noel runs into an old friend and classmate from the Military Academy.

Rachel conducts her own mysterious business as usual, porting from place to place. Kokonoe has her own agenda and sends Tager to carry out a mission. And Ragna works towards a full recovery with the help of some friends.

Kokonoe's little gambit with Ragna plays out. In the meantime, Jin is still searching for Ragna, but instead, ends up being found by Bang Shishigami, who wants revenge against Jin.

Tager continues to slowly track Noel. Noel finds Tsubaki, which results in a complicated showdown. And Rachel leads Ragna to where he needs to be and to confront what he already knows.

Hazama throws an obstacle in Ragna's way to buy himself some time. This encounter leads Ragna to have an entirely different sort of experience with Lambda.

As Makoto works to get Noel to safety, she explains her faith in Kokonoe and her doubts about Hazama. And Tsubaki finally finds Jin again, who is still struggling to deal with his recalcitrant weapon.

Noel and Makoto fight a losing battle against Hazama while Ragna fights Jin inside the Cathedral. Noel disappears, and Hazama reveals a secret to Ragna.

Hazama's interference keeps Ragna from using his powers. Noel is reborn in the Cauldron as Mu-12 and attacks her former friends.

Kokonoe and Rachel believe that Noel's transformation into Mu is irreversible, but Ragna refuses to give up on Noel.