A piece of kind advice if you happen to come to Tokyo, please ask for permission if you wanna take pictures of the girls and about 99% of the time, they will say "No." unless you have prove that you're from an idol scouting agency. 
You're doing it wrong; you don't take pictures of the girls directly, you take pictures of the scenery, that happens to have girls in it. If you're asked why, just say something like "I thought that building looked pretty cool" or "My friends would find that ad to be funny." Just, you know, make sure they're legal, because I don't want the FBI messing around on the forum.