在与戈鲁戈姆战斗后半年,本应取回的和平突然被怪魔界克萊西斯帝国打破。克萊西斯帝国的杰克将军想拉拢南光太郎作为部下,但光太郎不答应,于是杰克将军便将其变身机能破坏。 变身机能破坏的情况下,光太郎被扔往宇宙。在即将变为宇宙尘埃的时候,光太郎被神秘的太阳光线照射,其体内的帝王石亦产生了变化,光太郎也因此变成了新生的光之王子·“太阳之子”假面骑士BLACK RX,并展开了与克萊西斯帝国的战斗。As the show continues Minami Kotaro gets captured by crisis empire general Jak and offers hims to join with him and destroy earth. But Kotaro escapes from the crisis and falls through space which his belt "The Kingstone" gets the power of the sun and reborn as the child of the sun "Kamen Rider Black RX" and his old bike "Battle hopper" also reborn as "Acrobatter" and a new allie a car name "Rideron". The power of sun helps Minami Kotaro fight against general Jak and the crisis empire on a number of 47 action packed episodes.