To provide realistic bodies while preventing the corpses from moving, after a lengthy casting process the crew chose extras who could lie as still as possible. For the bath house owner Tsuyako Yamashita, this was not possible owing to the need to see her alive first, and a search for a body double was unfruitful. Ultimately, the crew used digital effects to transplant a still image of the actor during the character's funeral scene, allowing for a realistic effect.
Although the character of Mika was initially planned as being the same age as Daigo, the role went to pop singer Ryôko Hirosue, who had previously acted in Takita's Himitsu (Secret) in 1999. Takita explained that a younger actress would better represent the lead couple's growth out of naivety. In a 2009 interview, Takita stated that he had cast "everyone who was on my wish list".