Criminal Girls

I know I have to press O at a certain time, but I tend to get misses alot...what do I really need to do?

Watch the heart/s.

When they lock on to the girl's sprite AND change color, that's when you hit O.

It has to be both.
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http://momoiro-rakuen.blogspot.com/
I only review the games I like... and none of them are in eenglish.