These spectral twins are both the Moon King’s daughters and his most powerful and ruthless assassins. They are the sisters of Kubo's mother but have never treated family above themselves, only when obeying their father. Identical in voice and appearance down to their chilling Noh masks painted with a frozen smile, the Sisters are in charge of dispelling their father’s worries and hunting down his enemies. They do not need to eat, nor to sleep, and they shall not let anything stand in the way of them capturing Kubo and fulfilling the wishes of their father.
The Sisters both wear peasant hats with disturbing Noh masks covering their true faces. They also have dark black armor and capes made out of feathers. One sister wields a katana and the other a chain scythe. Both of the sisters have jet black hair that is loosely tied back.
One sister wields a katana, while the other a kusarigama. Aside from being somewhat omniscient, the Sisters have complete control over anything having to do with shadows and darkness. They easily create illusions of shadow and can float over the ground, negating the need to walk, even transforming into gliding rivers of black fog to sneak into places. The Sisters are capable of levitation and flight, as well as the ability to be extremely empathetic, such as anticipating incoming attacks and avoiding them with impeccable precision. Perhaps their most uncanny ability is their synchronization with one another, often finishing each other’s sentences, speaking in unison and seeming to know where the other sister is at all times.
As their basic appearance is virtually the same, the exact could be said for their personality. To be blunt, the Sisters are completely psychotic and the textbook definition of a persistent stalker. Cold, cruel, calculating, dark, creepy, and homicidal to the core, they take pleasure in ending anyone that is foolish enough to interfere with their resolution to catch Kubo. The Sisters are shown to be quite sadistic as well, enjoying the suffering and sorrow of others and laughing uncontrollably when they saw how frightened Kubo was in their presence during their first confrontation. They hate and despise anything that is pure or light, preferring to embrace the darkness of night as an old friend.
- The Sisters are both voiced by Rooney Mara, who previously had roles in The Girl with the Dragon Tattoo and Pan. This also explains why the voices of the sisters are eerily identical.
- The Sister's names are Karasu (attacked on Kubo's boat) and Washi (attacked at Hanzo's fortress). In English, their names translate to "crow" and "eagle", respectively.
- The Sisters are based off of the female Samurai warrior: Tomoe Gozen who was a prominent warrior in Feudal Japan, and had a face claimed to be as beautiful as porcelain.
- The jet black feathered cape sported by the two Sisters included 861 laser-etched feathers, each uniquely sized and shaped, giving the appearance of a large raven cloak.
- Their porcelain noh masks are traditionally costume items used in Japanese theatre, and is a subtle callout to No-Face from Hayao Miyazaki's Spirited Away.
- Both the Sisters share a striking resemblance to Kagetane Hiruko from the anime: Black Bullet. Both have similar personalities-psychopathic and sociopathic, and both wear noh masks.
- LAIKA's puppet lab supervisor considers the masked identical Twin Sisters to be one of her career's highlights. Hayns says there's always a puppet that you're most proud of on a project, but the Sisters are the puppets she's "most proud of in her entire career."
- Since The Sisters are the sisters of Kubo's mother, they are technically his aunties...the very sinister and bloodthirsty type.