Gong Hyo-jin
Screenwriter Noh Hee-kyung and director Kim Kyu-tae said that by realistically exploring characters from a romantic comedy standpoint, their drama also aimed to address the discrimination and social stigma attached to people with mental health issues and other minorities. This was Noh and Kim's fourth collaboration; actor Jo In-sung had previously worked with them on "That Winter, the Wind Blows" (2013), while actress Gong Hyo-jin had starred in Noh's "Wonderful Days" (2001).