Become Beast After Saving Wanrenli

The protagonist Fujimaru Ritsuka and the time traveler Ji Yuqing were originally heroes who saved humanity, but they were sealed because of the fear of the clock tower. The two people, who were unable to fight back, were completely reduced to experimental subjects after being abandoned. The unwilling Ji Yuqing finally became Beast0. That day, black mud flooded the clock tower, and no one inside survived. Since then, there has been a pair of heroic twins in the world, Fujimaru Ritsuka who calls himself Savior and Ji Yuqing who calls himself Beast.