Movie
Description
Nia Teppelin, the disowned daughter of the Spiral King Lordgenome, was created by the Anti-Spiral as an artificial messenger. Sheltered and isolated within her father's palace, her only contact was with Lordgenome and Beastmen. After developing self-awareness and questioning her existence, Lordgenome exiled her into a canyon stasis pod. Simon discovered and awakened her during a battle using his Core Drill.

Initially curious and innocent due to limited experience, she learned about surface concepts like humans and cooking after joining Team Dai-Gurren. Her lineage caused distrust, particularly from Yoko Littner, but acceptance followed when encounters with Lordgenome's generals confirmed her exile. She became the team's cook despite her disastrous culinary experiments.

During the assault on Teppelin, she confronted Lordgenome about his abandonment and oppression. Witnessing Simon defeat him, she tried to save her falling father but resolved to face the future without him. Her unwavering belief in Simon strengthened his resolve.

Seven years post-war, with humanity thriving under Simon as Supreme Commander of Kamina City, Nia documented progress in letters addressed to the deceased Kamina, reflecting on the city's development and Yoko becoming a teacher. Simon proposed marriage. Nia initially refused, misinterpreting his words literally. After counseling clarified the symbolic meaning, she accepted.

During their celebration, the Anti-Spiral activated the Human Extermination System upon humanity reaching space. This triggered dormant programming within Nia, transforming her into their emotionless messenger. Circuits traced her skin, her attire shifting to a black bodysuit with glowing red lines. She announced the Moon's collision course with Earth in three weeks, blamed Simon's spiral energy, declared her human identity fiction, and coldly outlined the Anti-Spiral's goal to prevent universal Spiral Nemesis.

As the messenger, she repeatedly confronted Simon, asserting humanity's futility and escalating challenges. She retained Simon's engagement ring, a detail he later used to argue her true human feelings persisted beneath the programming. This allowed her to briefly regain her personality and end the Human Extermination System's control over Earth. The Anti-Spiral immediately transported her to their domain for data extraction.

Simon led a rescue mission to the Anti-Spiral homeworld. Upon liberation, her bodysuit dissipated, and Simon caught her in his coat. She participated in the final battle aboard Tengen Toppa Gurren Lagann. In the film adaptation, she piloted the unique Tengen Toppa-class mecha Solvernia during this conflict, fighting alongside the team despite knowing the Anti-Spiral's defeat would end her existence.

After the Anti-Spiral's destruction, she returned to Earth. Her existence, tied to them, began fading. She married Simon wearing white. During the ceremony, she expressed her love before fully vanishing. Her engagement ring remained, placed on a cross at a memorial near Kamina's grave.