Kou Taiki, known in her Sailor Guardian identity as Sailor Star Maker, is a central character in the anime Pretty Guardian Sailor Moon Cosmos the Movie. She is a member of the idol group the Three Lights and a core part of the Sailor Starlights. Taiki originates from the planet Kinmoku, which was ravaged by Sailor Galaxia. Alongside her comrades Kou Seiya and Kou Yaten, she traveled to Earth to search for their lost princess, Kakyuu. To conceal their identities and broadcast their search telepathically through music, they adopted the public personas of the male pop group the Three Lights. In the Cosmos film, Taiki is a female Sailor Guardian who takes on the disguise of a male high school student, genuinely enjoying her civilian life as a member of the Literature Club and writing poetry. She attends Juuban High School and plays keyboards and guitar for the group.

Taiki is the most intellectual and level-headed member of the trio. She is logical, analytical, and direct in her opinions, often serving as a voice of caution. She frequently criticizes Seiya for allowing his personal feelings for Usagi Tsukino to compromise their mission. Her intelligence rivals that of Sailor Mercury, and while she initially dismisses Mercury’s romantic idealism as impractical, the two gradually develop a mutual respect. Taiki is firmly dedicated to her duty to Princess Kakyuu, which initially makes her skeptical of the Earth’s Sailor Guardians. Despite her pragmatic worldview, she is the first among the Starlights to willingly allow Sailor Moon to purify an enemy rather than destroy it, hinting at a capacity for trust and personal growth.

In the narrative of Cosmos, the Starlights serve as crucial allies to Sailor Moon during the escalating conflict with Shadow Galactica. Taiki acts as the strategist of the group, protecting Sailor Moon as the other Guardians are systematically defeated. Her primary motivation remains the safety of Princess Kakyuu, though this evolves into a broader commitment to the fight against Chaos and a genuine bond with Sailor Moon. Along with her fellow Starlights, she is killed by Galaxia’s enforcers Sailor Phi and Sailor Chi, but she is ultimately restored. Her development throughout the film involves learning to balance her strict pragmatism with compassion, trust, and the value of friendship beyond her mission. As Sailor Star Maker, she transforms using the phrase "Maker Star Power, Make Up" and commands the attack Star Gentle Uterus, channeling her power through a microphone prop that matches the Starlights' performance aesthetic.