Beast Swords arc

The Beast Swords is an anime-exclusive arc focusing on the Tōjū, Zanpakutō spirits that were materialized by Muramasa but were not saved by their Shinigami causing them to go into a blind rampage.

The Tōjū Appear
A party is being held at Byakuya Kuchiki's mansion for the Sixth Division. Renji Abarai thinks this is a good time for the division members to fraternize with their captain, while Rukia Kuchiki notices how nervous everyone looks. Renji is surprised that Byakuya is hosting the party in his own home, while Rukia says he should be grateful Byakuya's looking after his men. Renji is whisked off by one of his underlings while Rukia is lecturing him. Annoyed, she returns to her quarters, when she hears a scream. She investigates, and discovers two interlopers smashing up one of the rooms. She moves to engage them, but remembers she doesn't have her Zanpakutō. She narrowly avoids their attacks, until Sode no Shirayuki arrives. She drives off one of them, but is ambushed when she tries to prevent him from escaping. She is saved by Senbonzakura. Rukia is shocked to see them in spirit form again and they tell her they never agreed to just be swords. Their argument is cut short by Byakuya's arrival, and one of the interlopers body combusts, revealing a Zanpakutō. Rukia, Byakuya, and their Zanpakutō spirits go over to Mayuri Kurotsuchi's place to ask him why there are still some Zanpakutō spirits around. He reveals that he never intended to return the spirits to Zanpakutō form. He continues to explain that the Zanpakutō that they encountered before were Zanpakutō spirits that were freed from Muramasa but they succeeded in killing their masters. While this would normally kill the Zanpakutō too, these are abnormal. Mayuri identifies this as something new, and tasks Rukia with capturing the one that escaped earlier and warns her that these Tōjū are effectively in constant Bankai.

Rukia ponders the difficulty of the task, but Senbonzakura and Sode no Shirayuki are both keen to fight. Renji arrives to inform them of a change of guard. Byakuya leaves Rukia in charge while he deals with this. Senbonzakura and Sode no Shirayuki both suggest large scale destruction to lure out the target but Rukia quickly discounts this. Sode no Shirayuki suggests that they have another party, this time at Tenth Division's headquarters.

Toshiro Hitsugaya is not happy with this, but allows it anyway since everyone needs a well deserved break from the battle with Muramasa. The plan fails however, as there is no sign of the target.

Rukia and Sode no Shirayuki have a quiet chat afterwards. Sode no Shirayuki reveals her inner turmoil regarding the events revolving around Muramasa. Rukia tries to remind her of the times when it was her who needed saving. This is cut short however when one of the Tōjū from earlier arrives. Capturing him proves more difficult when he assumes a tornado-like form but they are able to defeat him with a combination of her Shikai abilities and Kidō.

Rukia reports to Shunsui Kyōraku and Jushiro Ukitake that the Tōjū were delivered to the Shinigami Research and Development Institute and Ukitake reveals that similar reports are coming in from elsewhere.