Onew (Lee Jin Ki) 

Vocal instructor at SM Entertainment. Single Father to Lee Jae Hyun, lives near Cheongdam-dong. Reserved, doesn't talk much to any strangers. Formerly married to (late) Lee HyeMin. Strongly believes love cannot happen twice. Never gets to spend some time with JaeHyun, even if he wants to. Many girls still wants him to like them, but he just couldn't bring himself to like anyone else.

Byun Ji Young [Face Claim : Byun Ji Young]

Nerdy and jovial Dentist at a clinic near Cheongdam-dong, lives right next door to Onew. She likes kids and always tries to make them happy. Has no regrets in life, nor any sadness. Likes her work and does it whole-heartedly. Strongly believes love can happen as many times as one wants. Already had a boyfriend Sehun, but broke up with him for some reasons.

Lee Jae Hyun [Face Claim : Unknown]

Only son of Onew and HyeMin. Cute, funny and caring towards everyone. Wants his Dad to be happy, and want to see him smile like before. Likes to read stories and draw. Is a big lover of candies, will do anything to get them. Sometimes, he tries to make his Dad happy. Calls Onew by his name when he is angry. Hoping to have another Mom, even though he doesn't like any of the girls who come to meet Onew.

Sehun (Oh Sehun)

Fiance and ex-boyfriend of Ji young. Quiet sweet, but is short-tempered. Tries to mend their past relationship, but couldn't

Lee Hye Min [Face Claim : Jung Bo Ra]

Late wife of Onew, passed away in an accident. Was a former Model for Magazines and CF's.