Single men and women who just met exchange spare keys to each other's apartments!? What will become of the friendship between these two men and women that started with the desire to avoid dying alone!? "If you suddenly die, I'm willing to be the one to find you." Ki-chan, the manager of a recycling shop who is bad at tidying up, and Mr. Song, a freelance designer with obsessive-compulsive disorder. The two have exchanged spare keys to each other's apartments in order to avoid dying alone...!?