Yupe Tashu, a male human, held a position within the Galactic Empire as one of the most trusted advisers to the Emperor, Sheev Palpatine. While lacking Force abilities, Tashu was a dedicated historian of the dark side and an adherent of the Sith cult.
After the death of the Emperor during the Battle of Endor, Tashu became a member of the Imperial Future Council, a collection of influential figures who convened on Akiva to determine the course of the collapsing Empire. However, Tashu was apprehended when the rising New Republic discovered the gathering of Imperial leaders on Akiva and launched an assault.
Subsequently, Tashu was incarcerated by the New Republic on Chandrila. In 5 ABY, he successfully broke free from New Republic custody with assistance from Fleet Admiral Gallius Rax. Tashu later reappeared alongside the enigmatic Acolytes of the Beyond on the planet Devaron. During the Battle of Jakku, Rax and Tashu journeyed to the Jakku Observatory to initiate the Emperor's Contingency plan.
After Tashu had equipped himself with several Sith artifacts, Rax cast him into a borehole that descended to Jakku's core. Tashu perished, and the Sith artifacts he carried triggered a reaction that nearly annihilated Jakku. Tashu's demise marked the second-to-last phase of the Emperor's Contingency plan. Nevertheless, Rax's adversary, Grand Admiral Rae Sloane, successfully halted the Contingency by sealing the borehole, thus averting Jakku's destruction.

Yupe Tashu, a male human, functioned as an adviser for Darth Sidious, the Dark Lord of the Sith known publicly as Sheev Palpatine, who was the final Supreme Chancellor of the Galactic Republic and the inaugural Emperor of the Galactic Empire. Tashu's association with Sidious began in the closing years of the Galactic Republic. In 25 BBY, Adviser Tashu made a trip to the desolate Inner Rim planet of Jakku, situated on the fringe of the Unknown Regions. After arriving aboard Sidious' yacht, the Imperialis, he directed six droids to commence excavation of the Plaintive Hand plateau before returning to his vessel.
Unbeknownst to Tashu, he was under observation by a local human boy named Galli. Galli infiltrated the Imperialis but was discovered by Sidious, who presented the boy with a choice between death and fulfilling his destiny. Galli ultimately chose to serve Sidious and returned to guard the Plaintive Hand excavation site. The excavation site evolved into the Jakku Observatory, which formed part of the Emperor's network of Observatories spanning the galaxy. The Jakku Observatory housed a replica of the Imperialis, various Sith relics and artifacts, ancient computers projecting a map of the Unknown Regions, and a borehole leading to Jakku's core. The Jakku Observatory held a central role in Sidious' Contingency plan to dismantle the Empire should he meet an untimely end. Tashu maintained contact with the young Galli and reported the boy's unwavering loyalty. After Galli joined the Empire and adopted the name Gallius Rax, Sidious entrusted Rax with executing the Contingency.

In 3 ABY, the Empire defeated the Alliance to Restore the Republic, forcing them to flee from their headquarters on Hoth. The Commission for the Preservation of the New Order promptly issued an official statement in which Tashu, in a state of elation, declared that even on a remote and desolate world, the Alliance could not evade Imperial justice.
By 4 ABY, Tashu had risen to become one of the Emperor's most trusted advisers, placing him within the highest echelons of the Empire. He was even regarded as a friend by his Imperial master, to the extent that such a relationship was possible. Despite lacking the ability to wield the Force, a mystical energy field present in all living beings, Tashu had embraced the Sith cult, an ancient and malevolent order whose members sought to dominate the entire galaxy. The Imperial adviser considered himself a historian of the dark side, an aspect of the Force focused on fear, anger, and aggression. Tashu possessed at least one Sith artifact, a red metal mask with demonic features. Due to his close bond with the Emperor, Tashu was among the select few aware of his identity as a Sith Lord. He and Rax were also privy to the Contingency, which Tashu, according to his own accounts, assisted in by helping his master dispatch scouting parties into the Unknown Regions.

After a twenty-three–year reign, Darth Sidious perished during the Battle of Endor, when the Rebel Alliance destroyed the second Death Star battle station. The Emperor's sudden demise threw the Empire into chaos, and the Rebel Alliance transformed into the New Republic. In the aftermath of the battle, Yupe Tashu summoned Reyna Oskure — an Anzati mystic and high-ranking member of the Acolytes of the Beyond — to meet him on the planet Devaron, where the cleric had gathered with several other cultists. Upon Oskure's arrival, Tashu greeted her and commended her promptness before initiating a discussion about the current fragmented state of the Empire. Expressing his beliefs about the Force and the flow of power, Tashu, when pressed by Oskure to be direct, emphasized the need for the Acolytes to restore balance to the galaxy and defeat the nascent New Republic, confirming the Anzati's role in this endeavor. When Reyna informed Tashu that Grand Moff Ubrik Adelhard wished to meet with her, the advisor, who had his own plans for the defiant Imperial, instructed her to visit him and offer him the dark side's embrace. As Oskure departed, she cautioned Tashu to be mindful of his and his followers' desires, warning that they might become reality. Adviser Tashu, along with a few other high-ranking officials, agreed to meet on Akiva, a remote planet in the Outer Rim Territories still under Imperial control, to discuss the Empire's future.

During the summit, Tashu proposed that the remaining Imperial forces should retreat "beyond the veil of stars," seeking the source of the dark side and following the scouting parties that he and his peers had assisted Palpatine in dispatching. According to the Imperial adviser, this was the only way to rebuild a stronger, better-organized Empire that would lie in wait, and then strike the New Republic at the opportune moment.
Tashu's views clashed with those of other members of the newly formed Imperial Future Council. The self-proclaimed Grand Moff Valco Pandion advocated for an offensive strategy, utilizing the planets still under Imperial control to recruit more soldiers and employing their remaining starships to attack the New Republic and crush it in its infancy. The banker Arsin Crassus, on the other hand, favored negotiating with the enemy.
During the proceedings, Tashu also took the time to interrogate and torture a New Republic starfighter pilot named Wedge Antilles, who had been captured by the convener Admiral Rae Sloane while on a scouting mission.
However, the Imperial Future Council's existence was short-lived, as the New Republic disrupted its meeting on Akiva, inciting the planet's citizens to rebel against the Imperial occupation. During the ensuing battle, Adviser Tashu was captured by the enemy, along with General Jylia Shale.
Due to his refusal to cooperate with his New Republic captors, Yupe Tashu was confined to a bare cell with minimal comforts. He smeared the walls with food waste and drew strange symbols and maps. The New Republic guard assigned to watch over Tashu was a Chandrilan man named Windom Traducier, who was secretly an agent for the Imperial Fleet Admiral Gallius Rax. In 5 ABY, Tashu was visited by the former Imperial loyalty officer Sinjir Rath Velus and his friend Temmin Wexley, who had joined a group of rebels dedicated to hunting down Imperial war criminals.

After some delays, Sinjir managed to force the guard to open the door to his cage. Tashu recognized Sinjir, who returned the greeting and then asked him about Imperial prisons. After some rambling, Tashu reluctantly told Sinjir to visit the Siniteen prison builder Golas Aram on the planet Irudiru on the edge of Wild Space. Utilizing this information, Sinjir and his team successfully freed a hundred prisoners from the automated Ashmead's Lock prison on the planet Kashyyyk including Temmin's father Brentin Lore Wexley. However, this turned out to be a ruse by Rax to use the prisoners to attack the New Republic leadership.
During the attack, Traducier freed Tashu from prison. After being reassured that Traducier had not come to kill him, Tashu thanked the darkness for saving him. Traducier then directed Tashu towards a ship on Docking Platform E-22. When Tashu queried about Shale, Crassus, and Pandion, Traducier revealed that Pandion was long dead and that he had murdered Shale and Crassus. When Tashu inquired why, Traducier replied that he had received orders to kill them and to free Tashu. Traducier clarified that Rax was the new Emperor and that Rax served Sidious. Tashu praised the late Sidious for having a plan before making his escape.

In the months following the attack on Chandrila, Yupe Tashu escaped to Jakku, where the self-proclaimed Counselor to the Empire Gallius Rax had brought the Empire in order to test their mettle. Due to his close connection to the Emperor, Tashu and Rax were among those privy to the Contingency, the late Emperor's plan to destroy the Empire in the event of his death. On Jakku, Tashu watched as Rax killed his former master during the Counselor's time on the planet, the Anchorite Kolob. Tashu regarded this death as an offering to the dark side.
Yupe Tashu then informed Counselor Rax that he had a visitor in the form of one of the Emperor's sentinel droids. The sentinel droid informed the Sith cultist and Counselor Rax that Grand Admiral Sloane was traveling with Niima the Hutt's convoy to the Jakku Observatory. Subsequently, Rax ordered the Observatory's turbolasers to bombard the convoy before Yupe Tashu.
Tashu secretly led the Acolytes of the Beyond, a cult he intended to use to reinstate the dominance of the dark side. He recruited many Acolytes, including a Pantoran woman named Kiza, whose Force visions may have been induced by Tashu using a Sith artifact. Tashu provided an associate of the Acolytes, the Sith cultist and assassin Ochi of Bestoon, with forbidden Sith texts.
Later, Tashu journeyed to the Colonies planet of Devaron, where a cell of the Acolytes of the Beyond had assembled for an attack on a New Republic outpost near the Karatokai Mountains. This was part of a series of coordinated strikes against New Republic targets throughout the galaxy. Among the Acolytes were Kiza, her lover Remi, and Kiza's close friend Komat. Remi had stolen a lightsaber from the archive beneath the Peace and Security station in the Corellian city of Coronet City. As the master of this group, he gifted Kiza the mask of Viceroy Exim Panshard at the wishes of the venerable specters of fallen Sith. As reasoned by Komat, Tashu knew better than to wear the mask and be lost to Panshard's presence, so he intended to use the possessed-Kiza as his tool. Luke Skywalker later reasoned that, with Sidious dead and the Empire in pieces, Tashu hoped to rule the galaxy himself. Tashu himself, however, believed that Sidious still survived in secret and needed to be revived.
When Remi attempted to seize the mask for himself, Tashu reprimanded the youth for angering the venerable specters. As punishment, Tashu seized Remi's lightsaber and handed it to Kiza. During the attack on the New Republic outpost, Kiza fully embraced the dark side and entered into a homicidal rampage. Overcome by the dark side, Kiza murdered Remi with the lightsaber after he tried to recover his prized weapon. The incident revealed to the Acolytes that Tashu was their leader. Kiza spent much of her time with Tashu and became lost to the mask, with Komat and Kiza herself both even believing she killed Tashu at one point.

During the Battle of Jakku, Yupe Tashu accompanied Counselor Rax, Brendol Hux, Armitage Hux, and Rax's locally recruited child soldiers to the Jakku Observatory. While the Huxes and the child soldiers boarded a replica of the Emperor's luxury yacht Imperialis, Tashu and Rax entered the Observatory to initiate the Contingency. After making their way past several computers which the Empire had been using to calculate safe routes through the Unknown Regions, the two men entered a hallway containing artifacts from the old Sith Empire including a red mask, a white lance, a bloody banner, and a black holocron.
Tashu donned the Sith artifacts and carried the holocron, which caused him to grow paler from touching it. The two then crossed a walkway which extended over a deep borehole which led to Jakku's core. Before Tashu could give a prayer to the Sith, Rax told him that Sidious would be pleased with them. Tashu responded that they had activated the Contingency and called on them to give a prayer to the darkness. However, Rax interjected and asked Tashu what he would say to the Emperor when they saw their Master again. Before Tashu could give an answer, Rax threw him over the walkway.

Tashu struck a rock and died instantly. His body then plummeted down the borehole into the planet's core. Given the immense energy contained within the artifacts, they triggered a chain reaction that caused Jakku's mantle to fracture. As part of the Contingency, Rax intended to destroy Jakku and the surrounding Imperial and New Republic forces. He and a select group of Imperials would then journey to the Unknown Regions to rebuild the Empire.
Ultimately, Rax's plans were thwarted by Grand Admiral Sloane and the New Republic operatives Norra and Brentin Wexley. Sloane led surviving Imperial forces into the Unknown Regions, eventually forming the First Order, whose technologically advanced military, concealed from the wider galaxy, was incorporated into Darth Sidious' vision decades later for a unified galaxy under his rule—the Final Order.

Adviser Tashu's age was difficult to discern from his appearance. He possessed beady eyes and a face marked by dark striations. Despite his impeccably white teeth, he had a frightening, snake-like smile. He wore plush purple robes with bundled, puffy sleeves ending in tassels, and an emerald hat. Like other Imperial advisers, his clothing choices were reminiscent of the sartorial extravagance of Naboo noblemen.

Yupe Tashu, a religious extremist with a feverish gaze, remained steadfast in his dedication to the Empire and Darth Sidious. His commitment to the Empire superseded any personal desires or requirements. While Tashu considered himself a devout loyalist, figures like the former Imperial loyalty officer Sinjir perceived him as an irrational zealot. Simultaneously, within the Empire's leadership ranks, Grand Moff Valco Pandion openly mocked Tashu's pronouncements about the dark side, dismissing them as irrelevant during the Akiva summit. Tashu's unwavering loyalty to Sidious fueled his conviction that betrayal of the Emperor would result in eternal damnation. Although initially hesitant to accept Rax as the new Emperor, Tashu was appeased by Windom Traducier's assurance that Rax was serving the late Emperor's interests.
As a devotee of the dark side, Tashu presided over a cell of the Acolytes of the Beyond, a Sith-worshiping cult. Tashu was notorious for overseeing sentient being sacrifices and communicating with the spirits of deceased Sith Lords. He possessed a trove of Sith relics and masks. His peers, both Imperial and Acolyte, regarded Tashu, who also had teeth that were partially broken, as both insane and fanatical. Tashu was under the impression that the Contingency would serve as a means of punishing those he deemed "undeserving," failing to grasp that his own demise was also part of the plan.
Despite lacking Force abilities, Tashu asserted that he had received training from masters in an ancient Sith practice involving the red mask he owned. His connection to the dark side made Tashu resistant to interrogation. Furthermore, his association with Darth Sidious granted him knowledge of the Contingency and the Ashmead's Lock prison.
Tashu's collection included numerous Sith artifacts, such as kyber crystals and weapons. Notably, Tashu possessed a collection of Sith masks, which he distributed to deserving Acolytes following consultations with the specters of fallen Sith.
Yupe Tashu made his debut in Star Wars: The Aftermath Trilogy by Chuck Wendig.
In Shadow of the Sith, Komat states that Kiza killed Yupe Tashu sometime after the Acolytes' stay on Devaron. Conversely, in Aftermath: Empire's End, Gallius Rax stabbed Tashu and threw him into a chasm during the Battle of Jakku. Later, Shadow of the Sith mentions Kiza killing Tashu after killing Remi. Adam Christopher addressed the conflicting accounts of Tashu's death on Twitter, stating, "Yes! But... not yet".