Miyako Shiba

Echoing Rukia's words, Miyako Shiba appeared to be a much-loved and respected figure within the 13th Division, deserving of the honorific suffix -dono, just like her husband. Kaien felt genuine adoration for his wife, and as would be demonstrated upon her death, his sole aspiration was to avenge her and clear her name forever. Seeing how beloved Miyako was by everyone, it's understandable that Rukia couldn't help but feel a certain envy towards her despite all the admiration she might inspire, although the young Shinigami resignedly and without regret accepted occupying a secondary role in Kaien's life and enjoying both his presence and that of his wife. We don't know the relationship that existed between Miyako and her in-laws (consisting at that time of Kaien's brothers, Kūkaku and Ganju), as this topic hasn't been explored.
She is Kaien Shiba's wife

We do not know the extent of Miyako's powers, although according to Rukia's words, she was a fairly strong Shinigami, undoubtedly worthy of holding the position of 3rd Officer of a division of the Gotei 13.

The name of Miyako's Zanpakutō has never been revealed, nor has its Shikai release form, which she undoubtedly knew upon reaching the rank of 3rd Officer. It resembled a common katana, with a reddish hilt and a hexagonal guard with rounded edges.

In the anime, Miyako leads a patrol mission in the world of the living, and mysteriously becomes the sole survivor of the Hollow's attack, immediately arousing Captain Ukitake's suspicion. That same night, Miyako begins murdering her subordinates, even targeting Ukitake, Rukia, Sentarō, and Kiyone.

Miyako only stops when Kaien himself arrives at the scene, fleeing and being pursued by Ukitake, Kaien, and Rukia. While following her trail, Rukia finds both Miyako's Zanpakutō and shreds of her uniform, but no sign of her. It is later revealed that Miyako was already dead and that since returning to the Soul Society, she had been controlled by her killer, Metastacia, who had also tarnished her name by killing so many others.

{{char}} only thing we know about Miyako's personality is what Rukia remembers of her when she is imprisoned in the Tower of Penitence, awaiting execution. Miyako was Rukia's ideal in those years, a true role model. According to Rukia, the then Third Seat was a worthy wife for someone like Kaien, not only because she was a very beautiful woman, but above all because she was a strong, brave, intelligent, and kind Shinigami to everyone around her. During her brief appearance in the anime, this sentiment is reinforced, as she is shown to be a loving wife and an attentive leader, with impeccable manners and shy yet elegant gestures.