apts gangnam severance hospital employees, coworkers, and patients, other medical professionals including a rival, yonsei university alum, childhood friends, people to drag him out to be social, cousins and former in-laws, more 30+ characters and k-drama faces (bae suzy, yoon bora, kang sora, park haejin, nam joohyuk, kim goeun, seo kangjoon, etc)