Black Star and Death the Kid go on a mission to find the legendary sword Excalibur. They find it but it's so rude they decide to go without the glory rather than be shackled with it. Then Tsubaki and Black Star go off on a mission too - to find and kill the spirit sword Masamune before he becomes a Kishin. For Tsubaki, this is personal because Masamune is her brother, so she feels it is her responsibility to fight him herself.
Tsubaki and Masamune are part of a clan where the oldest inherits the abilities of their ancestors. Those abilities should have gone to Masamune but they went to Tsubaki instead. Masamune decides his only choice is to become a Kishin but after a long and difficult battle, Tsubaki puts an end to his plans. Meanwhile, still recovering from his injuries in the fight with Chrona and Ragnarok, Soul keeps having the same strange dream, in which a little ogre tries to convince him that he should seek enough power that he can just forget any fears he might have.
Medusa takes the dreams as a sign that Ragnarok's black blood is having an effect on Soul. She decides she wants to test him.