Academia Island, south of Japan's Izu Peninsula, belongs directly to the United Nations World Science Agency. The island is equipped with the most advanced facilities, where top scientists selected from around the world carry out cutting-edge research. Everyone on the island is working tirelessly towards one goal: launching the giant space satellite "Space Academia". They all hope that once it reaches orbit, it will carry out experiments impossible on the ground, developing new medicines, food and resources that will solve the Earth's crises and benefit all humankind.

The world's most advanced school, "Science Academia", stands on Academia Island. Its students come from all over the world, the elite of the elite. Under the guidance of the principal, Dr. Hoshi, they study the very latest science day and night.

Yusuke Amamiya, Jou Ohara, Megumi Misaki, Takuji Yano and Mari Aikawa, as well as Kenji Tsukigata, Rui Senda and Gou Omura, are all students at Science Academia.

One night, Yusuke, Jou, Megumi, Takuji and Mari are working late on experiments with the "space activity reinforced suit". Just as they are celebrating the first signs of success, a mysterious aircraft lands nearby. Three figures emerge from the darkness and walk towards it. The five look closer and are shocked to recognise Kenji Tsukigata, Rui Senda and Gou Omura.

Yusuke steps forward to ask what is going on, but suddenly Tsukigata turns, draws a laser gun and fires at them! At that moment, Takuji and Mari, still wearing the experimental reinforced suits, throw themselves in front of their friends. The laser pierces the suits and kills them both. Tsukigata and the others board the mysterious aircraft and fly off, leaving Yusuke, Jou and Megumi standing in shock, holding their motionless friends. They cannot understand why classmates of so many years would do such a thing.

In fact, Tsukigata and the other two had passed the test of a mysterious organisation, the "Armed Brain Army Volt". Deeply impressed by the talent of Volt's leader, "Great Professor Bias", and convinced by his theory that only superior geniuses should rule the world, they accepted his invitation to become his personal disciples at Volt's space base, "Zuno Base". Because Yusuke and the others had discovered their secret, they killed to keep it.

Two years after Tsukigata and the others disappear comes graduation day at Science Academia, which is also the day the Space Academia is to be launched. As everyone on the island watches with bated breath while the satellite slowly rises, a squadron of mysterious fighters appears and attacks both the Space Academia and Academia Island. Under relentless fire, the Space Academia finally explodes, scattering debris across the island. In an instant the whole island is engulfed in flames, and cries of grief fill the air!

After the bombardment, one of the mysterious fighters lands on the ruins of Academia Island. Out step Tsukigata, Senda and Omura, missing for two years, who announce that they have joined Volt and are now "Dr. Kemp", "Dr. Mazenda" and "Dr. Obular".

But Yusuke, Jou and Megumi had prepared for this ever since the incident two years earlier. Unable to hold back their rage, they instantly put on combat suits improved from the reinforced suits of two years before, transform into "Red Falcon", "Yellow Lion" and "Blue Dolphin", and strike back as Choju Sentai Liveman! However, Volt is far too powerful and sends out the "Disconnect Brain" to attack. Even after the three bring out their three large fighting machines, "Jet Falcon", "Land Lion" and "Aqua Dolphin", they gradually find themselves outmatched.

Then the three find Dr. Hoshi, who has miraculously survived the explosion. He urges them to hurry to "Cape Hope" and to combine their three powers. Soon afterwards, Dr. Hoshi gives his life to protect a pregnant woman.

Following his instructions, Yusuke and the others reach Cape Hope, where they discover the giant mobile undersea base "Gran Tortoise" and the female robot "Colon". Dr. Hoshi had also witnessed the tragedy two years earlier, and, foreseeing the existence of a mysterious enemy, had secretly built all of this. Colon hands the three a system disc that lets Jet Falcon, Land Lion and Aqua Dolphin combine. This is what Dr. Hoshi meant by combining their three powers! Liveman sets out again, merges the three machines into "LiveRobo" and defeats the Disconnect Brain.

But the long battle has only just begun...