Eons ago, a cube–like peaceful planet named Quarton, populated by shape–shifting living bricks called Tenkai, was ravaged by a war between two opposite factions: the Corekai and the Corrupted led by the ruthless warlord Vilius who desired to obtain the source of Tenkai Energy for his own purposes. However, the only ones who were strong enough to defeat him were the Tenkai Knights: Bravenwolf, Tributon, Valorn and Lydendor. Facing defeat, Vilius unleashed the mighty Tenkai Dragon, who was later defeated by the four Knights and its fragments were scattered across the planet. These heroes were never seen again, but the Corrupted have returned more powerful than ever.
Now on planet Earth in the year 2034, four teenage humans named Guren, Ceylan, Toxsa, and Chooki find an interdimensional portal to Quarton where they are chosen by the Guardians to become the new generation of Tenkai Knights and prevent Vilius to take control of both worlds.
(Source: Wikipedia)
— Description from AniList community (anilist.co).
