A Jedi apprentice was a child with Force-sensitive abilities. These children were recognized by the Jedi Order and inducted into a Jedi clan to undergo training in how to use the Force. Upon successful completion of their training, an apprentice could ascend to become either a Jedi knight or a Jedi guardian. Only Jedi knights, deemed worthy of wielding a lightsaber, were permitted to carry one while serving the lords to whom they had sworn allegiance; Jedi guardians were not considered suitable for this weapon.
Kouru believed that, despite her parents' desire to raise her, the Force dictated that she belonged to the Jedi and, consequently, to the Empire's lords. Thus, she was taken from them. She, along with many others her age, joined the Sith rebellion that was being spearheaded by the individual who would later be known as the Ronin.
During the Ronin's imprisonment under the Jedi lord Hanrai, one of the guards was a young Twi'lek boy named Yuehiro, who was an apprentice within Hanrai's clan. Yuehiro's thoughtful inquiries prompted the Ronin to offer him a veiled warning to exercise greater caution. The Ronin's opinion was that inquisitive children like Yuehiro were unlikely to advance to the higher echelons of the Jedi Order, especially if they dared to question their lords. However, they might be considered useful for activities like spywork or strategic planning within the guardian ranks. Furthermore, Jedi apprentices who were perceived by their lords as lacking sufficient physical prowess, such as those unable to run, were also destined to remain within the guardian ranks.