Ulube was originally Neo-Japan's representative in the 12th Gundam Fight who made his way to the finals, but was defeated by Master Asia. Since then, he became obsessed with power, believed that power was what ruled the Universe, and that the Gundam Fights were a facade where it was simply the stronger nations that defeated the weaker nations.
After Ulube learned the existence of Dr. Kasshu's project, the Ultimate Gundam, from a jealous Dr. Mikamura, he saw it as the answer to complete his goal, and plotted that it was the key to have Neo-Japan become the eternal ruler of the Universe, something that he kept secret from Dr. Mikamura who was unaware of Ulube's true desire. Leading a unit of soldiers, they raided Dr. Kasshu's Lab, but it went wrong where Dr. Kasshu ordered his son, Kyoji Kasshu, to flee with the Ultimate Gundam to prevent the Military from obtaining it and Mrs. Kasshu was shot trying protecting her son. While in pursuit, Ulube personally witnessed the Ultimate Gundam become the Devil Gundam from the impact of the crash, and destroyed all the mobile suits expect his, which left him with a scar that he supposedly covered with a metal plate. The reality was that he was infected with DG Cells and only wore the mask to hide that fact.
After Ulube had Kyoji framed as a scapegoat and had Dr. Kasshu placed in cryogenic suspension to silence him, once Dr. Mikamura revealed that the Devil Gundam's self-recovery would complete during the 13th Gundam Fight, Ulube decided for Dr. Kasshu's other son, Domon Kasshu compete as their new representative for the 13th Gundam Fight. Ulube also chose for Dr. Mikamura's daughter, Rain Mikamura to accompany despite that Dr. Mikamura was uncomfortable to involve her in that mission. Throughout the series, Ulube faked sympathy for Domon's situation and also pulled favors for him all for the purpose to one day re-obtain the Devil Gundam.
After the 13th Gundam Fight had ended and Kyoji had died to halt the actions of the Devil Gundam with Domon's help who was now aware of the truth, Ulube went into action, had the remains confiscated, and intended to reuse it for Military purposes. Once his men obtained the research notes from the late Wong Yunfat, Ulube learned that a female, the giver of life, would make a better host to the Devil Gundam than the body of a man. Ulube decided for Rain to become the new life core unit especially with it, and it became easy since Rain had left Domon after she found out the truth about her father's involvement in the Devil Gundam incident. Though Dr. Mikamura had given up on their plan thanks to Rain convincing him, once Ulube mentioned on what he planned to do with Rain, Dr. Mikamura was shocked and tried to help Rain escape only to be shot for his efforts.
Placing Rain into the body of the Devil Gundam, it completely merged with the Neo-Japan Colony and placed the colony on wartime alert. After the citizens were secured in the shelters and Ulube killed the remaining Military personnel and took full command, he then sent out a message to all the colonies and stated the removal of the Gundam Fights and that Neo-Japan would remain as their rulers. Despite the Neo-America Colony's attempt to attack, Ulube had the advantage. Domon then arrived, angry that Ulube had manipulated him all along and Ulube decided to finish him off. Although Ulube was close, Domon's Shuffle Alliance teammates arrived and saved him. Once the wounded Dr. Mikamura sacrificed his life to give them a fighting chance by releasing Dr. Kasshu's capsule into space and heeding Domon to save Rain and tell her not to blame herself for his actions, the Shuffle Alliance entered the colony and fought through Ulube's traps and released the escape capsules for the citizens in space.
Ulube responded by facing them in the Grand Master Gundam, revealed that he was completely covered by the DG Cells, became a complete servant to the Devil Gundam, and lost his mind to where he was part of the Devil Gundam's A.I. Unit's plan to eliminate the Earth. Though Ulube was able to overcome the Shuffle Alliance, through sheer power, he was killed when the five Shuffle Alliance members used their Gundams to combine their power into a single attack. Ulube's last words was the futility in defeating the Devil Gundam, and he was unaware that Domon and Rain eventually destroyed the Devil Gundam together.