Since there's no summary, I figure I'll post this for anyone curious. 
Basically, main character buys a cheap camera after finding out that his friend/crush has a thing for photography. The camera he buys is an old instant print one and, trying to impress her, he shows it to her. She's ecstatic and requests him to take a photo. She leaves before the photo develops. His co-worker that, more than likely, has a crush on him asks to see the photo. They both grab the photo and she turns into the girl he took a picture of. She then tries to seduce him. 
Also, there's a fellow that's recurring and seems to a shady guy. So, although there's no proof, NTR warning.