/jp/ - Otaku Culture

>The Nintendo 3DS has a camera. Two of them, in fact. One on the inner face and one facing outward. Project LovePlus for Nintendo 3DS uses the inner-facing camera to recognize your face and make sure your virtual girlfriend stays loyal to you.
>Famitsu reports that if someone else picks up your Project LovePlus game, your girl won’t recognize them, and say things like: “Who are you?” Konami are calling this feature the “Boyfriend Lock,” and say it’ll help players feel closer to their virtual girlfriends.

http://www.siliconera.com/2010/12/26/project-loveplus-on-3ds-has-a-boyfriend-lock/