During Shirou's delivery of the cutting-edge VITA system to his associate, he encounters Amane Mao, a superhuman girl boasting the ability to lift automobiles. The main purpose of the VITA system is to eliminate ERRORs, enormous cybernetic beasts that caused widespread destruction in Old Tokyo fourteen years ago.
Out of nowhere, an ERROR emerges and proceeds to wreak havoc. Despite Shirou's unsuccessful attempt to activate the VITA system, his colleague becomes an ERROR casualty, leaving him with no alternative but to team up with Mao and put the superweapon to use.
Henceforth, Shirou embarks on an exhilarating adventure as the male overseer of the VITA system at St. Liddel's Girls' Academy.