The new recruit is fueling discussions and debates within the unit "5121". Cold and haughty, the young May Shibimaru does not seem to reach unanimity. However, she will be the victim of the Casanova of the barracks, Takayuki Setoguchi. He will however be trapped by his female colleagues, because of a micro hidden under a desk.

It's Christmas again and Mai finally decides to reveal her feelings for Hayami.