The opulent painting is one of the pieces of artwork available in the Animal Crossing series games. The painting is Czech, art nouveau artist Alphonse Mucha's "Zodiac" poster made in 1896. The portrait is of a woman with the zodiac symbols behind her.
This painting is a lithograph-- an authorized copy of the painting by the artist or a skilled craftsman. Originally, this painting was done by Alphonse Mucha and finished in 1897, but now it cannot be viewed because it is part of a private collection. It appears that this poster is an elaborate advertisement for a show of some sort.