a peaceful civilization exists where advanced robots and the ancient way of life go hand in hand. But one day, a golden robot named Meca One leads the robots to revolt against the humans. Fights between the humans and robots break out, unleashing uncontrollable energies that divide the mountain in two. The humans eventually overcome the robots and cast them into the gorge. The humans build bridges to link the two halves of the mountain. The most important bridge they build is the Tenchi (天地 "heaven & earth") Bridge. Some humans, including Sensei Keiken, fear that the robots might come back someday so Sensei Keiken promptly begins to construct armored battle machines for defense. But before the humans' preparations are complete, the robot legions, armed with battle machines of their own, catch the humans by surprise and quickly seize control of the southern half of the mountain. More powerful than ever, their primary aim is to completely drive humanity from Sentai Mountain. Sensei Keiken hurriedly recruits new pilots to man the battle machines and Exo-Force is born. The Exo-Force storyline for 2006 culminates in the Battle of Sentai Fortress when Meca One unleashes an all-out assault on the humans. After a narrow victory, Keiken decides that Exo-Force is too vulnerable in the Sentai Fortress and that they need an "edge" to defeat the robots. The 2007 storyline centers around Exo-Force's discovery of the legendary Golden City at the top of Sentai Mountain and mysterious secret codes therein which could be used to unlock powerful technology. Keiken's hope is that this technology will provide the crucial key to defeating the robots. In the 2008 storyline, the northern side of the mountain begins to be conquered by the robots and many Exo-Force pilots are held captive. Among the lot, Sensei Keiken is captured, and is being held captive by the robots in the jungle at the base of Sentai Mountain. The remaining Exo-Force pilots must rescue their leader in this hostile jungle environment that holds the secret to what gave the robots life and the will to destroy. This plot was not resolved and the theme was discontinued after a single online comic. Main characters Humans : Hikaru is serious, silent, and wants to win. He prefers to work solo, but has learned to count on his teammates. He is a natural tactician and commander, though he can seem cold or overly