The experiment titled "The Sixth Dimension Experiment" aimed to open the sixth dimension (Secht) in our reality among the total of eleven dimensions. However, this endeavor had disastrous consequences - 110 million people lost their lives, and 12 countries were reduced to ruins. Himeka Yuki, the mastermind behind the experiment, bore complete responsibility for its failure and consequently faced eternal banishment from reality. As a measure to prevent another catastrophic incident like this, the world's scientific leaders formed a monitoring agency called "Zeien" to regulate scientists' technology and actions.
It has been a decade since the devastating incident mentioned earlier. Takaomi Yuki, Himeka's younger sibling, finds the "Time Machine Destination" device that his sister granted him before her banishment. Suddenly, the device brings forth a lively girl clothed in metallic armor that Takaomi has never seen before. She greets Takaomi with the words, "Takaomi-san! To save Earth, pull out your lance and ride me!" Driven to uncover the truth behind the device and the girl's appearance, the two embark on an adventure that transcends time and space.
