Teppei had spent 11 years under the tutelage of a cryptic woman named Karen. Now, he had his sights set on attending a scientific conference to reunite with his older brother, Kotaro Takamiya. But alas, his familial plans were thwarted when Aramis, in an attempt to abduct Kotaro, massacred everyone at the congregation. In his mission to rescue his kin, Teppei chances upon a damaged mechanical stallion christened B't X, which he jolts to life with his own blood. With the help of his trusty steed, Teppei plunges headfirst in a race against time to liberate Kotaro from the grasp of the elusive Machine Empire.