Mikoto is a lone samurai in training born of the prestigious Misaka Clan. Her mission? To defeat the 5 Samurai Warlords on a mission to discover who killed one of her two sisters. Journeying with her.. is a ninja of the Shirai Clan, A member of the royal Index Clan, and a Ronin of the disgraced and unlucky Kamijou Clan. In the ancient Japanese city of Akademi, these samurai must face one battle after another... and Mikoto must also learn one thing.. How to actually use a sword for one.. Hopefully the Ronin Kamijou can teach her before she enters an actual fight.

Abused, almost raped. Kuroko Shirai is broken. Though learning soon that she has a talent for killing, she joins a agency called Judgement as it's soon to be Ace, killing all the strongest top criminals without mercy or a second thought. But after meeting a certain scientific railgun what will happen? Will she open up her heart or remain cold and unfeeling forever?