When a mysterious avatar takes control of Umesato Junior High's network, ensnaring students and robbing them of their possessions, Kuroyukihime rallies Haruyuki Arita and Nega Nebulus to investigate. As other schools grapple with the same crisis, the group sets out to uncover the truth behind the phenomenon. Meanwhile, with Haruyuki's impending physical evaluation threatening his ability to partake in future battles, Chiyuri Kurashima assumes the task of preparing him for the crucial examination to safeguard their legion's integrity.