From Nookipedia, the Animal Crossing wiki
Katrina (ハッケミィ, Hakkemii) is a blue female panther, with dark purple eye makeup and bright orange eyes. She can tell the player their fortune, and appears in all Animal Crossing games. In Animal Crossing she has a male voice like Gracie and Saharah (who are both male in Japan), but in later games she has a female voice.
In the original Animal Crossing, Katrina's tent will appear randomly in location and by date. She can tell the player their fortune for 50 Bells using her crystal ball. Copper can let the player know when she will appear in their town a few days in advance. Her tent is open from 9:00 P.M. to 9:00 P.M. the next day. On New Year's Day, she will set up a desk by the Wishing Well, giving the player a letter with a fortune in it. The effects of the fortune last the rest of the day.
Katrina's role in Wild World is generally the same as in the original Animal Crossing, however, Katrina uses cards to read the player's fortune rather than a crystal ball. There are only three possible outcomes in Animal Crossing: Wild World: good luck, bad luck and neutral. The card that Katrina reads out will be in either a natural or inverted state, with natural state usually meaning good luck and inverted state bad luck, but this is not always the case. Katrina's tent will appear randomly in front of the Town Hall on a random weekday. She can tell the player their fortune for 100 Bells. Additionally, she can tell players how compatible they are with someone else for 100 Bells or cleanse their spirit (which clears the effects of bad luck) for 10,000 bells.
In City Folk, Katrina can be found in the city in the building furthest to the right, telling fortunes or lucky charms for 100 bells. She will greet the player by the player's star sign (e.g. if the player's birthday is on March 15th, she will call the player a Pisces). She can tell the player their fortune once a week (effect lasts for the rest of the day), and/or she can give the player a charm for that month, usually involving strange tasks. However, the player who is given the fortune cannot obtain the charm - the task stated by Katrina (such as planting a number of trees or pulling a number of weeds) needed to be done by a visiting player and only they could obtain the charm. One would have had to cooperate with a friend to do the prescribed tasks in each other's towns to obtain the charm. No matter what the player asks her to do, she will have something drop on their head. It will make the player wobble and be "dizzy" (stars appear around the character's head). It should be noted that Katrina uses her crystal ball in this game, like in Animal Crossing, and her fortunes generally have milder effects than in previous games.
Here are the six possible effects that could occur after Katrina reads a fortune:
Before the Nintendo Wi-Fi Connection was shut off on May 20, 2014, out of town players could get one of the following beneficial effects the next day, as stated by Katrina, from a lucky charm:
In Animal Crossing: New Leaf, Katrina visits the player's town in a tent at the Event Plaza on random weekdays and will tell the player's fortune for 500 bells. Once players in town have had their fortune told twenty times, and the mayoral player has spoken to Katrina after twenty fortunes have been told, the Fortune Shop on Main Street will become available as a public works project, which requires 340,000 bells to complete. Completing the project will allow the player to have their fortune told every day, although Katrina's tent will fail to show up in town any more.
Note that the player does not need to have a fortune read at all in order for the player's outcome to change, because Animal Crossing: New Leaf has a 'luck' system that determines money, item, and other outcomes for that day. For example, good money luck will increase the amount of money that villagers and the money rock give, but bad accident luck will cause the player to trip and fall, which has confused many players, who question why the player appears to be tripping for no reason. However, Katrina will suggest an item (or category of item) during her fortune reading that will improve the player's luck until 11 pm when worn. When the Fortune Shop opens, Katrina will sometimes sell a Celebration Hat or Tingle Hood (from the Legend of Zelda series) for 10,000 bells that removes the effects of bad luck.
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