Juju Tsukuyomi is the mother of the protagonist, Sasami Tsukuyomi, and the previous Miko of the Moon who held that position before her daughter. She has yellow eyes and blonde hair that reaches her chest, giving her the appearance of an adult woman. Juju died when Sasami was still a young girl, but her concern for her daughter's well-being led her to break a fundamental taboo. From the underworld, she watched as Sasami grew increasingly apathetic and abandoned her sacred duties as the shrine maiden, which Juju could not accept. Driven by a fierce maternal love and a sense of responsibility, Juju made the forbidden decision to return from Ne no Kuni, the land of the dead, to set her daughter back on what she believed was the right path.

Juju's personality is defined by a strict and determined nature, though she is also clumsy when it comes to expressing her deeper feelings. Her outward demeanor is often cold and severe, and she is willing to use extreme methods to achieve her goals, especially when she believes it is for the good of her family. Despite this harsh exterior, her actions are consistently motivated by a deep and unconditional love for her daughter, and she treasures the memories they shared. Her return to the living world triggers a significant conflict, as she actively opposes the Three Evil God Sisters, Tsurugi, Kagami, and Tama Yagami, whom she sees as obstacles to correcting Sasami's behavior. During their battles, Juju demonstrates formidable spiritual powers befitting her former status as a high priestess, and she manages to hold her own against the divine sisters. Ultimately, she is defeated by the combined might of the three Yagami sisters, with Tama Yagami's spiritual power playing a key role in her downfall.

Following her defeat, Juju's role in the story shifts from antagonist to ally. Recognizing a greater threat in the form of Tamamo-no-Mae, a powerful spirit possessing Sasami, Juju teams up with Tsurugi Yagami to save her daughter. This alliance leads to a deep reconciliation, not only with Sasami but also with the Yagami sisters, as Juju comes to understand and respect the choices her daughter has made. Rather than returning peacefully to the afterlife, Juju is reborn through a ritual known as Kami-umi, or divine birth, using Sasami's body as a vessel. This new life, however, comes with a heavy price, as it is granted for only a very short period of a few years. For a time, she is also entrusted with the Power of the Supreme God, a tremendous divine force.

A complex and central aspect of Juju's character is her relationship with her younger brother, Ruza Tsukuyomi, whom she has loved deeply since childhood. Their passionate relationship is the reason Sasami was born, being the child of Juju and her own brother. Even after her rebirth, her love for Ruza remains unwavering, though she is prone to intense anger when she discovers the strange and perverse habits he developed during her absence. In the story, she also refers to Kamiomi Tsukuyomi as her brother, though the exact nature of their connection is left unclear and mysterious. Through her journey from a deceased former priestess to a returning enforcer and finally a reborn mother, Juju Tsukuyomi's story is one of fierce dedication, difficult choices, and the powerful, often messy, bonds of family.