Just when you think the cast could not get any better for the upcoming drama "The Heirs," another promising actor is added to the credits. Casting got off to an excellent start with stars Park Shin... Hye and Lee Min Ho in the lead roles. Then fans of the band CNBlue and the dramas "You're Beautiful" and "Heartstrings" were teased with the possible addition of CNBlue's Jung Yong Hwa as the third member of the love triangle. Jung Yong Hwa briefly considered the role but then declined it, citing a busy music schedule. He disappointed fans that were eager for a third onscreen relationship between him and Park Shin Hye. However, his replacement was also a popular choice. Choi Jin Hyuk, who recently played Lee Seung Gi's monster daddy in "Gu Family Book," signed on to play Lee Min Ho's "perfect" older brother. But that wasn't the end of the casting good news. This week three more names were added to the list, Kang Ha Neul, Krystal Jung and ZE:A's Park Hyung Sik. Kang Ha Neul, who currently appears in the drama "Monstar" and was in "To The Beautiful You," will play Lee Hyo Shin, the student president of the school that Park Shin Hye and Lee Min Ho attend. His character is well connected, having a grandfather who is a government minister and a father who is the public prosecutor. Krystal Jung of the girl group f(x) has been cast as Rachel Ryu, but there is no word on what her character will be like. Krystal previously appeared as Ahn Soo Jung in "High Kick: Revenge of the Short Legged." Last but not least in casting additions is Park Hyung Zik of ZE:A. Park has already proven himself to be a fine actor when earlier this year he played Lee Jin Wook's younger self in the time travel drama "Nine: Nine Time Travels." He will play Jo Myung Soo, who comes from a wealthy family but is indifferent to the power money wields. Park's agency says that he will join the cast at the U.S. location for "The Heirs" in September as he is currently appearing in the variety show "Real Man." It has been said that most of the casting for "The Heirs" was done by the series writer, Kim Eun Sook, who also wrote "A Gentleman's Dignity" and "Secret Garden." "The Heirs" takes place on the campus of an exclusive school attended by the very wealthy. It has been described as similar in feeling to the American television show "Gossip Girls." "The Heirs" will air on October 9.