In the first episodes of "Secret Love Affair," Yoo Ah In does some electrically-charged, spine-tingling piano playing and it's hard to believe that he is not actually a piano prodigy, like the character he plays Lee Sun Jae.

If he is just faking being a piano virtuoso, he is a prodigy of an actor.

Kim So Hyung, the pianist who serves as classical music supervisor for the drama, praised the actor's dedication to the role.

"It seems like Yoo Ah In is a real genius," said Kim So Hyung. "He did not know how to play the piano before but I admire the way he is able to understand and follow along when I tell him something only once."

And he is not just moving his fingers to make it look as if he is playing.

"If I give him a difficult piece to learn, he returns the next day having memorized it," said Kim. "I realized that while he is able to immerse himself in the music and has exceptional concentration, he is really a very hard worker."

The pianist doubts that any other actor could rise to the challenge.

"If it wasn't Yoo Ah In in the role of the prodigy pianist Lee Sun Jae, I don't think it would be possible."

To prepare for his role, Yoo Ah In practiced the piano and listened to classical music on his cell phone.

In "Secret Love Affair," his 20-year-old character also never had formal piano lessons. He taught himself to play on a piano that was left in the home they moved into. His genius is discovered when he sneaks into a concert hall and plays a piece that he has just heard performed.

In the show's second episode he auditions for Oh Hye Won, who is an arts administrator at the Seo Han Arts Foundation. Played by Kim Hee Ae, she is a competent 40-year-old woman who leads an emotionally unfulfilled life, calming her erratic boss and immature husband.

The genius demonstrated by Lee Sun Jae brings joy to her life and she wants to promote his career. But in the process they fall in love with each other.

At one point in the audition she asks him to play another version of a piece and he confesses that he can't because he has never seen the notes. He taught himself to play it just by listening to it.