Parista wasn't always awake; the spirit woke up when the former Craftlord of Jade, Rumari, went too close to it. As a result, Parista cursed Rumari with a constant fever. Shintetsu fought to protect her, but was unable to finish his task of returning Parista to the spirit world; though he did manage to temporarily subdue it.

It was because of that event that Ureksa became the Craftlord of Jade and was consumed with the desire for revenge. Rumari was known as the majestic lancer and continued to carry the name even after she was no longer a Craftlord. She is not shown fighting, but right after Parista is finally sent home, an enemy army from Deigleya invades Wystern. This is not something the main character has to worry about, as the Craftlords drive them away.

At that point, only a few soldiers that have snuck into the city remain as their fleet retreats. It is said that Rumari would have been enough to take them all on by herself. At first, they are doubtful of such big words, but when the remaining Deigleya soldiers realize they're talking about Rumari the majestic lancer, they run away in fear. So basically they assure that Rumari can take on an army, thus its safe to say she's very strong and skilled.

This is all the more reason why Ureksa would be angry at Parista. He must have looked up to Rumari a lot. I can imagine him being the younger brother who believes that his big sister is invincible. It seems he wouldn't be the only one to believe that either. However, Rumari has never been a showoff or shown signs of over confidence in any way, even if her reputation precedes her. Ureksa was reminded that she's only human when she got too close to Parista, awakened the summon creature by accident and ended up suffering the consequences.

Ureksa's other relatives are not really mentioned, thus it can be concluded that Rumari might be his only living or at least close relative. Their sibling relationship reminds me of Magus and Schala, but I'll get to that point later. The point is that Ureksa was very close to his sister, thus her illness was a harsh blow for him. I can picture him being in denial and it's clear he was never really able to move on, even if Rumari tried to help him do so.

After Rumari got sick, she moved to Vance, a snowy port town near Wystern, so that the cold climate would help her health. As a result of sealing Parista, Shintetsu died, having used his own soul as an ingredient for the swords that sealed the beast. However, his task was not complete, since Parista was not returned to its world.

Angered by the apparent inaction of the Craftlords after the main crisis passed, Ureksa took matters into his own hands. He wanted to avenge Rumari against Parista. Rumari did not wish for revenge and had told Ureksa time and again not to seek it. Her wish was to live peacefully with her brother and boyfriend, Tyram.