The Enchanted Sword Masamune -- Break the Soul Possession: A Heart Sings in the Rain?
S1, E10: Black Star and Tsubaki face Masamune, and as the battle against the dark Weapon escalates, it becomes clear that Tsubaki must finish the fight alone.

S1, E10: Black Star and Tsubaki face Masamune, and as the battle against the dark Weapon escalates, it becomes clear that Tsubaki must finish the fight alone.