Her Japanese names translates to "Suspicious Cat"

(in Japan Blanca is a he and the rest of the world a she, so I'll be referring to her as she). I'm not too sure what she did in WW but in other AC games, she allowed the players to give her a face... really cute concept that turned sour (you may imagine why..

), then in NL I believe she was kinda like a "copy cat" apparently she would disguise herself as a villager and the player had 50/50 chances of guessing who the actual villager was, if you guessed correctly, she would give you a photo of that villager! This was part of April Fools.
I just like how "mysterious" she is and having a "blank canvas" kinda allows you to imagine her with unique features... but that might just be me lol