From Nookipedia, the Animal Crossing wiki
Blanca (あやしいねこ, Ayashīneko, Suspicious Cat) is a recurring character in the Animal Crossing series, appearing in every game. She is a white cat who asks the player to draw her a face. Blanca means white (feminine) in Spanish, which was derived from "blanco", which is "white" in Latin. Due to her fur color, this is most likely the origin of her name. Blanca also means "blank", referring to her blank, canvas-like face. Some say her gender is unknown, because she has no defining masculine or feminine features. She has a female voice in Doubutsu no Mori+, Animal Crossing and Doubutsu no Mori e+, even though she is listed as male on the Japanese Animal Crossing: City Folk website, but she has a male voice in Animal Crossing: Wild World and later, even in the non-Japanese versions. This is the same with Saharah, except Saharah has never changed her voice between games.
Although she does not have as developed a character as some of the others, she is shown to have a very spunky personality, similar to Uchi villagers, as no matter how much effort was put in to her face, she claims they just "scribbled something on". She also gets shocked easily, as shown when the player reveals to her in Animal Crossing that she lacks a face, and when the player unmasks her in Animal Crossing: New Leaf. In Animal Crossing: Happy Home Designer she claims to be in a prank war with Jack.
In Animal Forest + and Animal Crossing
In Doubutsu no Mori+ and Animal Crossing, she will randomly appear when traveling to other towns. When first meeting her, she will lack a face and ask the player if they could draw her a new one. She'll then appear in that town for a while, taking a walk with her new face. Strangely, in all official artwork in these games, she is never shown with a blank face, instead having a drawn-on face or simply scribbles.
In Wild World
In Animal Crossing: Wild World, she will appear if the "Mysterious cat" mode is turned on (which can be by using the telephone in the attic), and if the player has used Wi-Fi. She may appear randomly if the previous two conditions are met.
In City Folk
Blanca makes another appearance in Animal Crossing: City Folk. She may appear anywhere in the town as long as WiiConnect24 is enabled on both the Wii and the telephone in the attic. Like in the previous games, she will lack a face and ask the player to draw her one. Her face can be drawn a maximum of two times before she refuses any more in one day. If the player does not draw her a face, she complain that she cannot see anything. However, Blanca appears with a blank face only if she originates in the player's town; if the player has received Blanca from a registered friend, then the player will see the face that the friend drew, but the player may change or clear Blanca's face. Any of player's registered friends may receive her the next day.
In New Leaf
Blanca returns in Animal Crossing: New Leaf and acts as the leader of April Fool's Day. She dresses and impersonates as a villager from the player's town inside his or her house. Players must guess which one is the real villager. They do this by listening to a piece of revealing information each version of the villager says. Whichever says the wrong info is the fake. If you do not know, you can click on the below response (often "not likely" or "..."). You can find out what information is correct by telling other villagers that there is trouble. They will respond initially with shock and horror, but will soon calm down and tell you some information that the two villager versions will eventually use to reveal the fake. When the player knows who the fake is, they will say so, and be given a towel. They will then be asked to give the towel to the version of the villager they think is fake.If they get it right, they receive a picture of that villager. If the player is able to guess all the villagers correctly, they will win Blanca's picture the next day in a letter.
Happy Home Designer amiibo Card
When visiting Blanca's RV at the campground, the bottom screen will display the following:
Names in other languages