Koh Rabntah is a researcher for the Sons of Saint Coinach in Final Fantasy XIV tasked with researching and cataloguing the newly resurfaced Crystal Tower. Upon discovery of an orb in the unearthed tower, Koh was possessed by the spirit of the Allagan archmagus, Noah, known for her treatises on the cosmos and her oneiromancy. Noah was the court-appointed instructor for Unei and Doga, members of the royal bloodline, and transmitted her soul into an orb that survived for three astral and umbral eras until being discovered by Koh.
Koh's colleague, Syele, entrusts the Warrior of Light with finding Koh after she abandoned Saint Coinach's Find in Mor Dhona for Revenant's Toll. The Warrior discovers that Koh has been possessed by the soul of Noah that had transmitted her soul into the orb. Noah, discovering the Warrior of Light as being part of the Nominated Observers of Artifacts Historical, offers to use their oneiromancy to ascertain the group's discoveries within the Crystal Tower, creating oneiromatic pearls that would contain the memories of the Warrior of Light's expedition through the tower. Noah promises that if she found their discoveries worthy, she would impart some manner of knowledge unto them. Upon reviewing the Warrior of Light's memories, Noah deems it necessary to inform Koh's colleagues of some manner of the truth, and since then takes turns controlling the body with Koh.
Koh Rabntah is 28 years of age and a Keeper of the Moon Miqo'te of around 62.6 ilms in height, with pale skin, dark hair and fur and a long tail. She wears Inspector's Eyeglasses dyed Regal Purple and the Cotton Robes common among the Sons. Noah's appearance during her time alive in her own body is unknown.
Described as "timid", Koh Rabntah was not one to stray far from the expedition camp, which led to their worries when she left for Revenant's Toll. The archmagus Noah, meanwhile, is both boisterous and curious, bragging about her many famous deeds and taking over Koh to walk in the world again. Noah, for her part, considers the members of NOAH her disciples as they bear her name and is open to imparting on them a manner of knowledge. Following her observations of the Warrior of Light's journeys, Noah remains content with observing a world not preoccupied with the mistakes of the Allag.
Noah, in Koh's body, is seen holding a smoking pipe. It is unknown if Koh herself partakes in the vice or if it is solely Noah's.
Noah, like much of the Crystal Tower content, is based on events and characters from Final Fantasy III. In that game Noah was a powerful Magus that had as his disciples Unei, Doga and Xande, whom he gifted control over dreams, vast knowledge of magic and mortality respectively.