This is an excellent K drama in which Seo Kang Joon did very well. He did excellent in "Are you human too" but I think he did even better in this one. He successfully brought you into three different stages of his journey from a nearly OCD freak 20s to a mature middle age man and his unchanged love for his first love. The character's genuine love and sincerity are excellently revealed in the drama. Like his drama more and more. Looking forward to his next drama.