Kaguya is a spirit originating from the Miracle Flower above Tokyo. Adopted by the brilliant scientist Sarena Gashuuin, creator of Virtual Dream technology, Kaguya assumes the role of the popular "Virtual Dream Princess" within that system.

She manifests as a young girl with curled white hair and red eyes. Her attire includes a pink dress with white frills, a pink choker featuring a pale pink butterfly, gold bracelets with white frills, and pink-and-white shoes. A small pink hat with two white feathers completes her look.

Driven by a kind and earnest desire to fulfill everyone's dreams through Virtual Dreams, Kaguya nonetheless experiences loneliness due to Sarena's frequent absorption in research and responsibilities. Despite this, she holds deep respect and affection for her adoptive mother. Her abilities allow her to control and manipulate the Virtual Dream environment.

The use of her inherent power in developing Virtual Dreams placed severe strain on her existence, pushing her body to its limit and leaving her with little time left. During the film's events, she befriends Nodoka Hanadera after returning Latte to her, forming a central emotional bond.

The climax reveals Sarena captured members of the Yes! PreCure 5 GoGo! team to harness their Dream Buds, intending to use the Miracle Flower to save Kaguya. After confronting her mother, Kaguya is absorbed by Ego Ego, an artificial life form from Sarena's research, to grant it a humanoid form. To rescue her, Cure Grace receives power from the other Cures, transforming into "Dream Cure Grace" and then evolving into "Kaguya Grace" through the combined hopes and Virtual Dream energy of the entire city. This transformation purifies Kaguya, reviving her as a human girl surrounded by flowers, where she celebrates her birthday with Sarena.

Her name, "Kaguya," signifies "shining light in the darkness" or "bright night."