For one year, Master Swordsman Eiji Shinjo has been haunted by the memory of his battle with the renegade champion, Gaia - a battle that was cut short by the forces of the malevolent syndicate known as the organization. Denied victory, Eiji left the tournament followed by his opponents mocking laughter. Worse still, Eiji walked away no closer to finding his long lost brother, Sho. But now, a mysterious warrior is hunting down the champions of the previous tournament and using their own moves against them - and it looks like that person may be Sho. Who is this powerful new foe and who is his next target? Eiji and Kayin, his closest friend and greatest rival, struggle to unravel the mystery before they, too, join the ranks of the defeated. The answer lies at the heart of the Organization and its plans for world domination. At last, the ultimate battle between the greatest fighters in the world will be decided. But if Eiji loses, his friends - Ellis - may Die... (Source: AniDB)

The evil Gigatron has led his forces of Destrongers to Earth, where they seek to pillage the planet for its vast energy resources in order to fuel their war against the Autobots. If successful, the Destrongers will finally be able to tip the scale of power in the war to their favor, eliminating the Autobots and moving on to conquer the universe. To this end, the Destrongers kidnap the scientist Dr. Ohnishi, Earth's leading scientist on energy and natural resources. Dr. Oonishi's son, Koji, is contacted by none other than Fire Convoy, who takes the boy on a mission to rescue his father. Although Fire Convoy and the other Autobots fight valiantly, they are unable to rescue the doctor from the Destrongers. Now it is up to the Autobots and Koji to rescue Dr. Oonishi and protect the Earth and its resources from Gigatron and his army.

In the near future, humanity has taken its first steps towards journeying into the far reaches of the galaxy. Upon doing so they discover a huge race of insectoid aliens known as Space Monsters. These aliens seem dedicated to the eradication of mankind as they near closer and closer to discovering Earth. In response, humanity develops giant fighting robots piloted by hand-picked youth from around the world. Shortly after the discovery of the aliens, Noriko Takaya, the daughter of a famous deceased space captain, enters a training school despite her questionable talents as a pilot. There, she meets her polar opposite, the beautiful and talented Kazumi Amano, and is unexpectedly made to work together with her as they attempt to overcome the trauma of war as well as their own emotions.

Tottoko Hamutaro Hai! is the sequel to Tottoko Hamutaro, or in English, Hamtaro. The series revolves around the 15 original Ham-Hams in short 5-minute episodes. The Hai! series is animated differently from the original series, most notably, the head-to-body ratio is off, and it is also computer-generated in 3-D. (Source: Wikipedia)