Legendisc

Legendiscs (レジェンディスク Rejendisuku) are "secret items" capable of sealing away fearsome beasts. Such is their power that Dragotron was sealed away by Optimus Prime's Autobots using the Legendiscs. Legendiscs have the ability to transport humans and Transformers through time, and have also been known to enhance the natural strength, speed, and reflexes of humans who carry them. They have a variety of effects on transformers, from upgrading an individual transformer's form to allowing multiple transformers to combine.

Known bearers
There are six known Legendiscs. Several of the discs have been passed down as family heirlooms or have otherwise changed hands through the years.

Transformers Go!
Two factions in the Sengoku period both had Legendiscs—green and yellow—of their own, which they used as part of military standards.

The blue Legendisc was sealed within Dragotron's body.

The red Legendisc fell into the possession of the Japanese Tatewaki family, who regarded it as a "sacred mirror". One day, while Isami and Sekishūsai Tatewaki paid their respects to the sacred mirror, the Predacons Budora and Gaidora, who were tracking the Legendiscs, came across the sacred mirror and attempted to steal it. Isami attempted to flee with the sacred mirror on Sekishūsai's orders, causing the two Predacons to chase the boy. Realizing that the two demonic robots would cause destruction to Tokyo in search of the Legendisc, Isami tried to make a stand, but the Predacons simply threatened the lives of nearby bystanders. The Legendisc responded to Isami's desperation, summoning the Swordbot Samurai Team through Isami. When the Swordbots defeated the Predacons and their Jaki minions, red Legendisc connected to the Legendiscs in the past, transporting the Swordbots and Isami back in time to the Battle of Sekigahara. There, they saw the opposing armies each have a Legendisc of their own.

The azure Legendisc ended up in one of Nagoya Castle's shachihoko statues. The ninja Fūma clan were tasked with protecting this "sacred mirror", a duty a clan elder tried to emphasize to his grandson, Tobio. This duty was called to the test when two other Predacons, Bakudora and Judora, took the Legendisc. Tobio used his ninja skills to snatch the Legendisc away from the Predacons and, when he became enraged by the Predacons threatening innocent bystanders, inadvertently summoned the Swordbot Shinobi Team through the Legendisc. As with Isami, Tobio also enabled the Shinobi Team's ability to combine to help defeat the Jaki. Thanks to their Legendisc, Tobio and his Swordbots were also transported to the Battle of Sekigahara, where they also saw the opposing armies' Legendiscs.

Answers were forthcoming from Optimus Prime, who explained to the Swordbot teams and their human companions that the Legendiscs other than the three accounted for in the present could only be found in the past, and that a "time slip" caused by a connection of a present Legendisc with a past Legendisc would be necessary to acquire all of the Legendiscs. Unknown to them, Budora had sent a small drone to spy on them, learning of the Legendiscs' abilities as well. Using the Legendisc in Dragotron, Budora and Bakudora travelled to the past, where they took the green Legendisc from Musashi Miyamoto and attempted to change history. The Samurai Team detected the changes in time and travelled back to correct the changes. After meeting Miyamoto and battling the Predacons, the Samurai Team were unable to retrieve the green Legendisc, but at least removed the Predacon intrusion into history.

After Isami detected another Legendisc connection point near the Cybertron Satellite in Ginza, the Swordbot Samurai team traveled back in time again and discovered the green Legendisc now in the possession of Ryōma Sakamoto. Ryōma agreed to give Isami his Legendisc, and Isami used it to allow the Samurai Team to combine to face the threat of the upgraded Black Goradora. Unfortunately, due to some spectacularly bad timing, the disc was knocked out of Isami's hand just as GoGanoh's attack connected with Budora and Bakudora, causing it to disappear as Isami and the Samurai Team were returned to the present.