When university student Nishikawa finds a gun on a man's corpse on a nighttime walk in the rain, he becomes obsessed with the weapon. Nothing has ever made him so happy. But Nishikawa's personal life is starting to get more complicated: he finds himself romantically entangled with two women, while his biological father, whom he's never even met, lies dying in a hospital. Though his feelings for one of the women are growing, he still can't stop thinking about the gun—and the four bullets that came loaded in its chamber.
Nishikawa plans to fire the gun for the first time on a quiet mountain range, but one rainy night, he shoots an injured cat in the neighborhood instead. Soon, a police investigator is at his door, pushing Nishikawa to make a crucial decision: Will he take the ultimate step of killing a person, or abandon the gun forever?
