Sarena Gashuin, a scientist and representative of Dream Tech, created the Virtual Dreams system and the Dream Pendant. She possesses long black hair with messy, spiked bangs and wears red glasses, typically dressed in a white lab coat over a blue dress shirt, black dress pants, and grey shoes. Initially kind-hearted, her research aimed at creating a peaceful world gradually became an obsession. Despite this shift, she retains a conscience, demonstrating remorse upon recognizing her mistakes and maintaining unconditional love for her adoptive daughter, Kaguya, whom she also created.

Sarena deeply loves Kaguya but grows detached due to her escalating fixation on research, straining their bond though her fundamental care persists. She also created Ego Ego, an artificial life form that resents her neglect. Sarena's research causes a critical flaw: Kaguya, as a spirit of the Miracle Flower, faces a shortened lifespan and will die on her 14th birthday because her power fuels Virtual Dreams. To save Kaguya, Sarena orders Ego Ego to steal "Dream Buds" from the public, forcing the Miracle Flower to bloom. This plan involves capturing members of the Yes! Pretty Cure 5 GoGo! team to utilize their Dream Buds.

When Kaguya discovers Sarena's actions, she runs away, forcing Sarena to confront the consequences of her choices. Sarena intervenes to stop Ego Ego from capturing Kaguya, sustaining injuries. Later, after Ego Ego absorbs Kaguya during a confrontation with the Pretty Cure teams, Sarena's emotional outpouring contributes to Kaguya's purification and revival. Witnessing this, Sarena is overcome with joy, and the two share an emotional reconciliation. Kaguya awakens as a human girl surrounded by flowers, and Sarena celebrates her birthday.