During the press day for the upcoming post-apocalyptic action thriller The Book of Eli, out on January 15, Mila Kunis was happy to at least attempt to explain the story of Black Swan, the Darren Aronofsky drama about ballerinas that she's currently filming. Although she couldn't get too detailed, for fear of revealing something she shouldn't, she did explain that the film is a movie within the story of the "Swan Lake" ballet, of which the Black Swan is in the third act. However, she did detail the rivalry her character has with Natalie's. According to Kunis,

My character appears and is everything that she wants to be in life... She's not as technically as good as Natalie's character, but she has more passion naturally, and that's what Natalie's character lacks, and so it's a battle. It's a yin and yang.

Along with an intense training regimen to learn how to be a ballerina, since Mila claims to have two left feet, she also says that she's on a strict diet, which she's looking forward to leaving behind, once the film is done in February 2010.

Check out what she had to say after the jump:

You're currently working on the Darren Aronofsky film, Black Swan. Can you explain the basic story of that?

MILA KUNIS: Sure. Black Swan is a very hard movie to explain. It's Darren's movie. Natalie Portman and I play rival ballerinas and her character gets the lead in "Swan Lake." My character appears and is everything that she wants to be in life. Her character is very professional, very strict and very neurotic. And, my character is very loose. The talent that my character has in ballet comes naturally to her. She's not as technically as good as Natalie's character, but she has more passion naturally, and that's what Natalie's character lacks, and so it's a battle. It's a yin and yang. Ultimately, it's a story of Natalie's character going through a downward spiral, mentally, through "Swan Lake." It's such a hard movie to explain.

The film is being described as a supernatural drama. Where does that element of it fit in?

KUNIS: I have no idea how to explain it. Yes. I can't say anything. That's the problem. Her character is in a world that's just falling apart, all around her. And so, because everything is falling apart around her, crazy things start happening.

Are you involved in any of that craziness?

KUNIS: Yes.

In a very direct, confrontational way?

KUNIS: Yes.

Are you a bad girl then?

KUNIS: No. I'm not a bad girl. There's no protagonist and antagonist. There really isn't. I don't know how to do press for this because I cannot explain this movie, to save my life. There are no bad people in this movie. Although, Natalie's mother is not necessarily the greatest mother in the movie. I can say that. That would probably be the antagonist. But, as far as she and I go, it's just an unfortunate tale. If you know the story of "Swan Lake," the Black Swan is the third act. It's a movie within the show, so if you know the story of Black Swan, you'll get what the story is about.

KUNIS: Yeah. The characters are ballerinas dancing "Swan Lake," and the characters within the film mirror the story of "Swan Lake." That's the best way that I can explain it. It's a fascinating story.

What did you do for preparation to play a ballerina?

KUNIS: I'm training for a ballet movie, which is a thousand times worse than anything that I've ever done. I've been doing that for five months, and that has been the most physically strenuous thing I've ever done in my whole life.

Were you a fan of ballet before that?

KUNIS: I was aware of ballet. I've seen ballet, but I didn't realize what it was. I didn't realize what you have to put your body through, in order to look like a ballerina, walk like a ballerina and dance. You can't fake ballet. You can fake running. You can fake looking like your active and throwing things and shooting a gun. You cannot fake ballet. That's what I've learned. It's the craziest thing I've ever done in my life.

Why do it then?

KUNIS: Because I love Darren Aronofsky and, if anybody was ever going to get me to do it, it would be him. If I was ever going to trust anybody to make me look like a ballerina, it would be him. I have two left feet. Good luck! And, so far, it's been going great. But, oh my God! What I'm doing right now is, by far, the most physically strenuous thing ever.

Are you a Russian ballerina in the film?

KUNIS: I'm a ballerina from San Francisco, but maybe via Russia. We don't know.

What are you doing after Black Swan?

KUNIS: Eating.

You're on a strict diet regimen for that then, along with all of the physical training?

KUNIS: Yeah. I'm so hungry, all the time. I'm just going to eat and not work out and not do anything. I plan on doing nothing. I end Black Swan in February, and I am just going to be a couch potato for a good month.