Girl with a blue flower

Weight: unknown.
Height: unknown.
Age: judging by temperament, no more than 18

Teleportation (or some kind of transport ability)
Shown at the end of the prologue, when the Painting transported the Last Artist to the studio's pocket space. It's presumed it was also used when they lured the other six victims into that space.

Levitation
As has been demonstrated repeatedly, the Painting is capable of transporting the Artist from place to place, dragging him with the help of an unknown force. In essence, this can be compared to a poltergeist's ability to move objects.

Materialization
Drawing on her memories of the events she witnessed while observing the First Artist and the Model, Painting is able to materialize her motif in a pocket-sized space. This is demonstrated in "Day 2" and "Day 2+," when she materialized macaroons and a knife, then dematerialized them.

Soul Extraction
As demonstrated on Day One, the Painting is capable of extracting the souls of its victims to use for a variety of purposes. On Day One, the Painting uses the Last Artist's soul when he asks for paints to paint, and on Day Four, it uses it to light a lamp so the Last Artist can enter a replica of the Old Man's private room.

Alluring Aura
While not explicitly stated in-game, it is hinted at by the Sculptor's first available note and the character backstory notes found in the game's gallery section. This ability is clearly evident in the notes of the Homeowner and the Sculptor, when they begin referring to the painting as "she" rather than "it" before becoming obsessed with acquiring it.

In the painting, she is depicted wearing a gray dress with a white collar, a shawl (usually draped over her shoulders), a brooch, and a black bow at her chest. She wears a flower in her hair (which, as it turns out, is a replica of the Old Man's unsuccessful flower hair ornament). She has a slender build and youthful features. The only color in the painting that doesn't fit the monochrome palette is her eyes, which suffer from heterochromia (her right eye is red and her left eye is white). Her hair and skin are white.

The girl is very picky, impatient, and childish, which manifests itself in her fiery temper and frequent mood swings, especially at the beginning of the game. However, despite her childish nature, she is very meticulous about such matters as placement and color.

Although the painting was a portrait (and considered the First Artist's masterpiece, despite countless landscapes deemed unsuccessful by critics and other artists), it was locked in the basement of the First Artist's studio and never saw the light of day due to the painful memories it evoked in its creator. However, this only fuels her desire to be "finished," believing that if she were to do so, perhaps she could achieve what the First Artist failed to achieve.

It is still not entirely clear what prompted the artist to complete the painting.

After that, she began building a reputation as a haunted painting, luring all seven of her owners into another studio-like space she created. First, she lured the studio owner, the First Artist, then the Sculptor, the art gallery owner, the Explorer, the Collector, the Art Dealer/Buyer, and finally, the Last Artist (you).
The researcher's notes also mention that the painting is part of a series of other portraits called "Girl with a Blue Flower" due to the similarity of the models and the characteristic blue flower in their hair.