The kyber mirror of Shinsui Temple was a mirror made of kyber crystal that was housed within Shinsui Temple on the planet Rei'izu. Due to its reputation for imparting visions, the dark lord and the witch sought it during the Sith rebellion when they captured Rei'izu. The vision that the dark lord saw turned him against his Sith followers, and he became the Ronin.
The kyber mirror of Shinsui Temple was a mirror made of kyber crystal that was housed in Shinsui Temple on the planet Rei'izu. The mirror was perfectly circular with a flat surface. It was seated on a wooden dais that also served as its altar. Stories about its origin claimed it that it had either been found, created, or gifted by gods; other legends attributed divinity to the mirror itself. It was believed to reveal truth to beings who beheld it through the visions it imparted.
When the dark lord who had been a Jedi knight and the witch who had been one of his guardians led the Sith rebellion against the Empire and its Jedi clans, the Sith captured Rei'izu. After the monks and nuns of Shinsui Temple had been expelled, or killed if they refused to leave, the witch and the Dark Lord of the Sith approached the kyber mirror. For multiple days, the witch kneeled before it in a trance. The dark lord, impatient and frustrated, idly touched the mirror and saw a vision of unending war, not the peace he wanted for his followers. Overwhelmed, he struck the mirror with his fist and with the black current and white flare of the Force. The mirror shattered apart and a kyber shard was imbedded in his knuckles. He turned on his followers and began eliminating them while the witch remained on Rei'izu.
The former dark lord, abandoning his prior name to become only the Ronin, at some point removed the sliver of the mirror from his knuckles. Eventually, he traveled to Seikara Caverns on Dekien and left the kyber shard in a grotto. Ten years later, the shard was located by the Traveler and their master, the Jedi lord Hanrai, who entrusted them with the kyber. The crystal was placed within the Traveler's lightsaber.