Kūkaku Shiba

is an ill-tempered fireworks expert that lives on the outskirts of Soul Society and a personal friend of Yoruichi Shihōin. She is also the somewhat authoritative older sister of Ganju Shiba and younger sister of Kaien Shiba.

Appearance
She lives with her family in ridiculously-themed houses (which she changes in design and location regularly) on the outskirts of Soul Society. She is missing her right arm, which in the anime is replaced with a prosthetic, to which the reason of the loss of her right arm remains unknown. Kūkaku also appears to be as well-endowed as Rangiku Matsumoto. She carries a short-bladed sword on her back but it is unknown if this is her Zanpakutō or not.

Personality
Kūkaku is the acting head of the Shiba family, which fell from the status of nobility after her brother, Kaien Shiba, died. Because they knew only that Kaien was killed by a Shinigami, both Kūkaku and Ganju are distrustful of Shinigami when first introduced. After Kaien's killer, Rukia Kuchiki, explains how he died and apologizes, the Shiba make amends.

Kūkaku seems to have some kind of relationship with the Urahara Shop, knowing Yoruichi Shihōin and claiming to have worked with Kisuke Urahara in the past. She also seems to have a love for danger.

Soul Society arc
After an unsuccessful attempt to break into Seireitei after their arrival in Soul Society, Yoruichi leads Ichigo and his friends to Kūkaku, knowing that she has the means to get them into Seireitei, and asks for her help. The group is astounded by both Kūkaku's house, and her overall character. She leaves no doubt that she is the master in the house, strictly (if not brutally) disciplining Ganju and Ichigo when the two, after they realize that they already met in Rukongai, want to continue their fight which began there. They do so, but Kūkaku breaks it up when one of them crushes her pipe by accident.

Kūkaku then demonstrates the use of a special orb she develops. Sometime after they are able to use the orb properly, Kūkaku launches Ichigo, Yoruichi, and their friends, as well as Ganju - who decided to go with them - out of her cannon and into the Seireitei.

She later reappears after Jidanbō Ikkanzaka recovers from his injuries at the hands of Gin Ichimaru. She claims that she has unfinished business with Yoruichi. Sometime later, she and Jidanbō make their way to Sōkyoku Hill after Sōsuke Aizen reveals himself to be alive and a traitor. After Aizen and his forces are seemingly subdued, the Menos rescue him, Gin Ichimaru, and Kaname Tōsen, and both Kūkaku and Jidanbō watch them as they ascend to Hueco Mundo.

After the conflict within the Seireitei has ended, Rukia Kuchiki arrives and apologizes to both Kūkaku and Ganju about how she killed Kaien. She acknowledges that she felt guilty, but was too afraid to face both Kūkaku and Ganju to apologize to them beforehand. Kūkaku forgives Rukia, explaining to her that Jūshirō Ukitake had already told her the details of Kaien's death, and that she would forgive Rukia if she ever came to apologize. She then subsequently invites both Rukia and Ichigo (who arrives a bit after Rukia apologizes) to dinner with her before Ichigo and his friends return to the Human world.

Bount arc
Although she doesn't appear initially, Kūkaku sends Ganju to the Human world to assist Ichigo Kurosaki and his friends. When Ganju calls Kisuke Urahara an old man, Kisuke tells him that he's the same age as Kūkaku.

Later, after the Bounts infiltrate Soul Society, Yoruichi Shihōin decides to make Kūkaku's house their base while tracking the Bounts in Soul Society. When they are alone, Kūkaku asks Yoruichi why she wants them to stay with Kūkaku over staying in the Seireitei. Yoruichi informs her that Maki Ichinose, an ex-Shinigami working with the Bounts, has already broken into the Seireitei, and it would be more efficient to stay in a place that the Bounts haven't infiltrated yet. Nevertheless, Kūkaku agrees to assist Ichigo and his group.

Power & Abilities
High Spiritual Power: Kūkaku being of the Shiba family she possesses immense spiritual pressure.

Enhanced Strength: She strictly (if not brutally) disciplining Ganju and Ichigo when the two, after they realize that they already met in Rukongai, want to continue their fight which began there. They do so, but Kūkaku breaks it up when one of them crushes her pipe by accident.

Kidō Expert: The Kūkaku Cannon is a kidō-driven device making use of Kūkaku's special sphere-shaped inventions. Kūkaku uses an advanced Kidō technique to fire The Kūkaku Cannon. She also used a level 63 Hadō when they, along with Jidanbō, fought against the other three gate guardians.

Fireworks expert: Kūkaku has a knowledge of creating and using fireworks, allowing her to use them in combat when needed and she is better than Ganju.

Zanpakutō


Kūkaku possesses a sword, which is presumably a Zanpakutō as it is shown when she is activating the Cannon. It's name is unknown and resembles an ordinary katana. Kūkaku appears to keep the Zanpakutō on her back in the same style as her brother Ganju.


 * Shikai: Not Yet Revealed


 * Bankai: Not Yet Achieved

Quotes

 * (To Yoruichi) "Yes, that’s usually the case when you seek me out. …Is it dangerous?" (Yoruichi) "It’s going to be…"


 * (To Yoruichi) "Been a while since we’ve talked like this, my friend. Lucky for you, I enjoy danger."


 * (To Ichigo) "You ignorant dumbass! You gotta stay focused!"