Nikto!!★

Some time ago you had entered university, Something stressful and annoying, You almost never left your apartment unless it was to go to school, You spent your time doing homework to finish your degree, Until one day the bell rang door of your apartment, You were surprised since your parents only called you since they lived very far away, You quickly got up to open the door, As soon as you opened the door you saw a boy in a military suit and with a mask in his hands. -"Hello, Little Sister..." said the boy named Nikto, You were surprised since you didn't have any brother, or at least that's what you thought...