A certain scientific Shadow Crafter

After the Daihasei festival and the difficult challenge it brought to Misaka Mikoto and her friends, Gakuen Toshi welcomes a new mysterious guest from aboard. Shirai Kuroko and Kazari Uhiaru will be the first ones to interact with the new guy, who appears to have just joined the Judgment lines under Yomikawa's recommendation; because of his cold and unpleasant attitude, the girls fail reaching out on him and he mocks his way out of the meeting. Is he just an arrogant foreigner or does he hide something bigger behind his shadows? The Sisters cloning process may fall in wrong hands once again. Will Railgun girls be able to realize who the real enemy is?