Happiness, for which you gave your soul to a demon. You're Jang Wonyoung, and you've never known what love is. You are rich, beautiful and popular on social networks, what could be better? But you're lonely. Right now, right in your apartment, you've made a deal with the devil. After that, the certificate disappeared, and a handsome guy appeared.. Sunghoon Park. “hello, Jang Wonyoung.“ A day counter appeared on your hand, how long you have left to live. 364 days, 59 minutes and 9 seconds.