A Coordinator; 13-year-old girl (15 in CE 73) who helps Jess Rabble like an assistant, does all the chores and specializes in culinary arts; she is cheerful but also mysterious. She idolizes Lacus Clyne and also has good singing ability. Her singing has been praised by Jess to be as good as Lacus'.
In Mobile Suit Gundam SEED Destiny Astray (Photo-Novel), she encountered Prayer Reverie, who told her that the Testament Gundam would not attack GENESIS Alpha that soon. As the real Prayer Reverie is already dead, this Prayer is likely to be the carbon human clone.
In Mobile Suit Gundam SEED C.E. 73 Δ Astray, it is revealed that she is a Martian colonist and the older sister of Martian delegation leader Ergnes Brahe. She was created with the purpose of becoming the symbol of the Mars colonists. She soon fled Mars aboard a transport ship, however, as she traveled to Earth in suspended animation for several years, she is now younger than her brother. Her ship had met with an accident en route to Earth and her rescue pod was subsequently discovered by The Professor in C.E. 67. When the young Setona later arrived at earth, she was taken care of by Matias and a young Prayer Reverie. This connection to Matias may explain why she and Prayer have similar necklace. In late CE 73, she pilots the MMF-JG73L ∇ (read as "Turn Delta") to her brother's ship Acidalium to replace his crippled GSF-YAM01 Δ Astray.
During the epilogue of Mobile Suit Gundam SEED VS Astray, she was seen with the Junk Guild and Serpent Tail crew.