Yoshiaki enters a school notorious for its fights and violence. He chose to attend specifically for that reason, intending to become the strongest student there. Upon his arrival, he assists a girl named Homura, who is being bullied by some boys. When she subsequently asks him to be her "sword," Yoshiaki is unsure how to reply. It turns out that students at the school form pairs consisting of a "sword" and a "master." Others warn him against associating with the girl, who holds a "Rank F" status, suggesting she is unlikely to survive long. However, Yoshiaki is not keen on the idea of leaving her to die.