Rena Sayama, born Marie to alien parents who immigrated to Earth, was orphaned as an infant when xenophobic humans murdered her parents. Police officer Yosuke Endo adopted her, naming her Rena Endo. She later adopted the stage name Rena Sayama for her career as a popular idol singer. In the anime adaptation, Rena initially blamed Ultraman for her mother's death during a battle that collapsed a hospital, fostering resentment. This contrasted with her immediate support for Ultraman in the manga. Her perspective shifted after witnessing Shinjiro Hayata, as Ultraman, selflessly shield her from Alien Adacic's attack during a concert, beginning her gradual acceptance of Ultraman as a protector. Rena later discovered latent alien abilities inherited from her parents. These included an energy barrier that unconsciously activated to save herself and others during a building collapse in New York. Bemular, an enigmatic figure aware of her heritage, provided her with a specialized Ultraman Suit designated "Marie" for self-defense. She mastered the suit's capabilities and chose to actively fight alongside other Ultraman Suit wearers. Her character development led her to join the Science Special Search Party (SSSP) after proving her combat value during missions, notably using her barrier ability to assist teammates against powerful foes. She reconciled with Shinjiro upon learning his identity as Ultraman, strengthening their collaborative dynamic within the SSSP. In the anime's third season, Rena played a pivotal role in restoring public trust in Ultraman amid growing skepticism. Her efforts contributed to Shinjiro regaining popular support during the final battle against Mephisto and Edo. Across all media, Rena transitioned from a civilian idol to a recognized "Ultrawoman," balancing her performing career with her duties as an SSSP operative while maintaining a close relationship with her adoptive father. Physically, she stands 155 cm tall and weighs 45 kg. Her powers center on defensive capabilities, primarily energy barrier projection linked to luminous emissions from her hands.