Everybody Has Secrets (2004)
Everybody Has Secrets is a 2004 South Korean romantic comedy film. It stars Lee Byung-hun, Choi Ji-woo, Kim Hyo-jin and Chu Sang-mi. Because it has several sex-scenes, it is generally restricted to viewers under 18 or 21. Although the film wasn't a particularly big hit in South Korea it grossed $4,888,679 in Japan.
More at Wikipedia.