Infiltration
After having practiced and prepared themselves for the infiltration, Riko disguises herself as a working from the employment agency to introduce Aria and Kinji on the job. However her appearance makes Kinji feel sensitive after he had thought she was originally a girl named Kana. With that said, they show up at the mansion only to see their teacher being the one currently in charge of the place. After a week passes by of investigation and prep, they finally put the motion in action where as Kinji successfully retrieves the rosary, however the minute he gives it back to her and receives a kiss, Riko betrays them and reveals that she now has the tool she needed in order to defeat Aria.
Aired 01/07/2011EP 11 - Infiltration

Aria the Scarlet Ammo
Aria is a volatile girl who’s top dog in assault at a school for young mercenaries. When she discovers her classmate Kinji’s an ace, she strong-arms him into being her partner, but she isn’t the only femme fatale who wants a taste of his combat skills. His secret? He’s only a hotshot when he’s turned on! Aria gets Kinji for one mission, but he’ll end up with more than one finger on his trigger!
(Source: Crunchyroll)