Synopsis Of "Devilish Joy"

It follows the story of Gong Ma Sung, who grew up having a difficult life and experiencing hardships, yet still making joy from it. He is the successor to the Sunwoo company and excels in anything to do with the cranial nerve. From his difficulties, he is respected and looked up to as a brilliant man. One day, his kindness destroys his life.

Whilst trying to help a woman in trouble, he gets into an accident, and his life completely changes. He loses the ability to remember, and his memory is only limited to one day. Now, before he goes to sleep and forgets everything, he notes all the events from that one day. He wakes up with no recollection of the past and reads back on his notes to memorize.