Wow, that flashback finally made Koga's betrayal understandable, I guess I can't blame him for snapping after seeing how the council framed him and totally threw him under the bus. But seriously, when he started taking out all that rage on Muramasa, his own zanpakuto? That just broke my heart, I mean, a shinigami's weapon is supposed to be their soul, and seeing him destroy that bond just felt profoundly wrong.