Before co-starring in the upcoming drama "My Lovely Girl," both Rain and f(x)'s Krystal admitted to some mutual fandom.

In a recent promotional video for the drama, Rain had kind words for his 12-year-younger co-star.

"I have recently become a fan of Krystal so I am very thankful we are able to film this drama together," said singer-actor Rain, who is also known as Jung Ji Hoon. "You will be able to see a different side of Krystal through this drama."

In the drama, Krystal plays Se Na, a woman who dreams of becoming a songwriter.

When she found out that she was cast in the drama with Rain, she also had kind words to say about him.

"I can't believe that I'll be starring in a drama with Ji Hoon oppa," she said. "I never once imagined that something like this would happen."

In the romantic comedy, Rain plays Hyun Wook, a music producer and composer.

"I'm glad I got to meet such a cool character. 'My Lovely Girl' is a fun romance drama that everyone will enjoy, and all the actors are currently working well together."

Hyun Wook was originally in love with Se Na's sister who died. Then he meets Se Na and falls in love again. Hyun Wook and Se Na are two character who have experienced much pain. They will try to heal that pain through music and by loving each other.

Krystal, who like Rain, began her career as a singer, was attracted to the story because it is set in the music industry. She could also relate to Se Na's determined and positive character.

"I really want to try my hand at portraying Se Na, who overcomes all sorts of difficulties and ends up meeting her true love," said Krystal.

In the past Krystal had one other singer-actor k-drama boyfriend. In "The Heirs" Krystal played Lee Bo Na and Kang Min Hyuk of CNBLUE was her boyfriend. Although she made her debut in 2010, "My Lovely Day" will be her first leading role.

The drama is also a comeback role for Rain, who has not done a drama since 2010 when he appeared in "The Fugitive: Plan B." He recently filmed "The Prince" with Bruce Willis.

The drama will replace 'It's Okay, It's Love" on Sept. 17. But before that five of the cast members will appear on the variety show "Running Man."

Besides Rain and Krystal, the cast includes Park Young Gyu, Kim Ki Bang, Alex, Infinite's L, Hoya, BESTie's Hye Ryeong and Dani.