アンバー・サーストン (Anbā Sāsuton)
3 months (death)
Amber Thurston is the daughter of Renton Thurston and Eureka, and the older sister of Ao Fukai in Eureka Seven: AO. Although she is deceased and has never been seen in the series, her death serves as the catalyst of events leading up to her parents' decision to destroy the Scub Coral, and have her brother raised in a world with no Scub Coral or trapars.
Amber was born a few years after the end of Eureka Seven. After her parents were able to save the planet from being destroyed by the Limit of Questions, the Nirvash type ZERO told them to set an example to the humans by living together, and to bring forth a new evolution (Human-Coralian hybrid children). As it is their first child, it is shown that Renton and Eureka were happy; they were overjoyed upon finding out the baby was a girl. However, when they discovered that the Scub Coral was mysteriously disappearing, their happiness was put on hold (this was made apparent when Eureka was six months pregnant). During an experiment, which involved the Gekko, the Coral burst and, subsequently, took Eureka and the ship to the year 2025 of an alternate universe, where she met Ao, who knew she was his mother, but was shocked by the fact that the baby she was carrying was not him, but was, in fact, his older sister. He had been previously unaware of this fact. He then returned Eureka to her world, and she was reunited with Renton.
Before this incident, Renton and Eureka were told of the possibility that their child might be affected by high levels of trapar concentrations, due to being a Human-Coralian hybrid. That is, in simpler terms, no one knew for certain if the baby would live or die if she was born into such an atmosphere. Despite their concern, they chose to carry the pregnancy to term rather than choose abortion. Three months after her first trip into the past, Eureka gave birth to a daughter, whom she and Renton decided to name Amber. It is implied that Amber was a healthy baby, until she reached three-months of age, when the trapar concentrations reached a high level, and caused her body to turn as hard as stone, resulting in her death. It was later determined, that the existence of trapars in the atmosphere caused the cells of Human-Coralian hybrids to reject each other. The only time she is ever seen in the series is in episode 24, when Renton recalls her burial; in the scene, she is wrapped in, and covered by, a blanket. The death of their baby daughter greatly devastated Renton and Eureka, but it seemed that it was Renton who took the tragedy the hardest, as he was seen crying when Ao mentions that he knows he had an older sister. It is also implied that they were told not to have anymore children because the atmosphere, in which they lived, was (and continues to be) unsafe for Human-Coralian hybrids.
Renton decided to destroy the Scub Coral, going against all the hardships he and Eureka endured in order to protect the Scub Coral in Eureka Seven, because he was devastated and enraged by their daughter's death. Not only does Amber's death serve as the purpose for her parents' decision, but it also provoked their choice to send their second, at that point unborn, child, Ao, to the past, because the Earth's atmosphere, in the year 2012, would allow him a higher chance for survival. Renton and Eureka continue to mourn Amber's death, to the point where Renton cries profusely whenever she is mentioned and Eureka rarely speaks about her out of grief and guilt.
- In the front cover of the final Eureka seven DVD, Amber was depicted as having blue hair and porcelain complexion like Eureka, and blue eyes as Renton.
- Even though Eureka said she loved her daughter dearly, she rarely mentioned Amber after the child's death; possibly out of guilt that she chose to give birth to Amber while knowing the atmosphere in her world was too dangerous for her.
- Amber's death had a profound effect on Renton's mental state so much so that he completely disowned his previous vow to protect the Scub Coral in order to destroy it and was willing to give up anything to achieve that goal, including his relationship with Eureka and having Ao hate him.