Katanagatari Season 1 Episode 7

Bita, the Evil Sword

Having become annoyed with her brother's slow progress Nanami has decided to leave the island and collect the 'Deviant Swords' herself. However, her methods are far more ruthless than those of Shichika and Togame, and it isn't long before she acquires the Bita sword bringing the two sides into direct competition. As such the siblings are pitted against each other in combat but can the current head of the No Sword School really hope to defeat his vicious and gifted little sister; the 'true' heir to the title.