The head archivist in Cynas, Diadora first meets the Hero when he travels to Cynas seeking knowledge about the Chronicles. Diadora casually lied and claimed she didn’t know what the books are, and asked the Hero to leave them so she might study them and answer his question. However, he refuses. When Conon tells her she let a False Chronicle get away, she reminds him that the Hero remembered that the Flesaria Forest used to be a valley, and that was the more important problem.

After the archivists attack on the Hero’s castle is repelled, she recruits Dirk to the Order, playing on his jealousy at not being able to use the marks of the stars, as well as his own feelings of inadequacy.

Diadora possesses the incredible ability to open Gateways at will and travel to any destination she pleases, provided she had been there previously. This power is the result of her key-shaped staff. As such, when the Hero moves the Chronicles and his base of operations temporarily to Pharamond, Diadora manages to infiltrate the castle and steal the books. Diadora reveals that False Chronicles are actually from other worlds in the Infinity that had been destroyed, and that there is a True Chronicle which contains the past and future history of the current world, including where world fusions would occur. When those worlds are fused together, it displaces the world that wasn’t destroyed, and any people caught in it are utterly erased from existence. She considered it luck that when the 9th world fused, that the area that fused without any people, but she needs the power of the False Chronicles so that knowledge of where fusions will occur can be revealed, and they can happen without loss of life. However, the Hero doesn’t buy her story, as it doesn’t explain the philosophy of the Order and the war it’s causing. Diadora laments, and sends the Hero and his entourage into the Ravine of Infinity. She then returns to Cynas.

Diadora's confidence in her values is tested when Valfred makes the 10th fusion happen in Janam, wiping out the Magedom and it's million citizens. Valfred responds that more people would have died had he not done that, citizens who had accepted the doctrine of the Order would have perished. Diadora is then tasked with luring the Hero and his party away from the False Chronicle of the desert world by using her staff, a False Chronicle, just in case the Hero’s Company had someone who could track the Chronicle, which works when Luo-Tao scouts the world. It was the True Chronicle of the world she hailed from, which was destroyed by the One King and fused with the current world. She joins the Hero’s team, her faith already shattered by Valfred’s plan, as she wanted to use the Chronicles to prevent such loss of life. Diadora helps the Hero by opening a gate to Cynas to attempt to steal the True Chronicle, but due to the intervention of Sophia, Beardsley, and Dirk, is only able to escape with Nova, who angrily betrayed Valfred.

Diadora scouts out the 11th fusion after discovering it northwest of Pharamond, and names it “Rarohenga” which meant “hell” in the language of her original world. Although Valfred claims the Chronicle before she can, she manages to steal it from him when the Hero assaults Cynas. She also scouts out the 12th fusion and claims the Chronicle of Peaceful End there.

After the One King’s fall, the Gateways to other worlds disappear. Diadora can still use her Chronicle to travel around the current world, and does so, helping the various cultures rebuild. One day, she disappears without a trace.

Diadora is revealed to be a Wanderer and having come from their original world, when Hotupa discovers that “Rarohenga” means hell in his language as well. Diadora replies that she never tried to hide this fact, but she merely never brought it up. - Matt620