text: In 2005, he once again played characters of completely opposite temperament. In Rules of Dating, he plays a dirty-minded, scheming high school instructor who sets his mind on a pretty student teacher played by Kang Hye-jung, while in Boy Goes to Heaven he plays a young boy who suddenly finds himself an adult one day, ala Tom Hanks in Big.
  2006 saw him return to work with acclaimed director Bong Joon-ho in the big-budget monster movie The Host which went on to become the best-selling Korean film of all time.
  Murder mystery Paradise Murdered was a surprise hit in 2007, with Kyu Hyun Kim of Koreanfilm.org calling Park "an inspired choice for the ostensible protagonist, projecting fatigued compassion and cold calculation in equal measure, his obsidian pupils glistening with streaks of chilling obsession."
  In 2008, he starred in the period drama Modern Boy, a dramatic love story set in 1930s Gyeongseong or old Seoul, when Korea was under Japanese colonization (1910–45). Park played the role of a rich, hedonistic playboy who cannot care less that his country was colonized, then falls head over heels in love with a beautiful and mysterious independence fighter (Kim Hye-soo).
  After small supporting roles in Shim's Family (also known as Skeletons in the Closet), and Good Morning, President, Park joined the ensemble cast of A Million as one of eight participants who take part in a TV reality show in Perth, Australia but discover that they must literally survive to win the prize of 1 million dollars.