As I understand it, the basic plot of the show goes something like this:
Thousands of years ago, when the wicked witch, Bandora, was imprisoned in a container with her minions, the tribes realised that perhaps years later, she might escape. So the best warrior of each tribe was frozen. In the 1990s, Bandora is accidentally released by two astronauts investigating the planetoid Nemesis when it drifts near Earth. The warriors are released from hibernation and begin to fight Bandora as the Zyurangers !
The team roster is as follows:
Geki - TyrannoRanger
Leader of the Zyurangers, Geki is the Prince of the Yamato Tribe. Geki also possesses a strong sense of responsibility and justice
Goushi - MammothRanger
Goushi is the oldest of the original 5 team members. He is the knight of the Sharma Tribe. He supports Geki with his superior intelligence and physical strength.
Dan - TriceraRanger
Dan is the knight of the Etof Tribe. Vibrant and carefree, he often fearlessly dives into battle, and usually cheers up the team.
Boy - TigerRanger
The knight of the Dyme Tribe, Boy is the youngest Zyuranger. He is, though, a disciplined fighter, often displaying agile, acrobatic moves.
Side note: When Saban edited the show for American audiences into MMPR, they gave the Yellow Ranger a sex change!
Mei - PteraRanger
Warrior princess of the Lycia Tribe, Mei is the sole female ranger. She displays feminine sensitivity and care for the others, but also has a courageous fighting spirit.
Burai - DragonRanger
Burai came along later in the series as a villain, but later saw the error of his ways and joined the team. Burai is actually Geki's elder brother. He turned to evil because of his hatred for his brother. He discovers soon after he joins the team that his time is limited.
Barza
Barza is the mentor of the rangers and woke them up after Bandora was released.