Fun little thing I found.

...This wasn't common knowledge? xD

I have to say that you are a bit late, but I myself only noticed this around December (never touched a character for anything other than their feathers or to hear their voice lines in their personal pages). But I'm sure that there are some that don't know this. I actually forget it even exists from how little I use it IMO

I use it all the time, and pretty much have ever since I started back in February. I know how you feel though - I only realized a month or so ago that it says the friend's username in the upper right corner of the visiting hero lol. Before then, I always just looked at the set, and went through all my friends looking for whoever had that set on their unit. xD