Lee Kang-joo (Soo-hee?s secretary & ceramic pottery maker) / actress Chae Rim
She's an adorable woman who exudes a natural confidence. She wears a smile all the time and is fiercely loyal to her friends.
She's also loyal in romantic relationships. She believes that loving someone is equal to making a vow to that person.
When she became Seung-hyun's tutor, she found that he kept clinging onto her.
Even when she cut off all contact with her friends and took a trip to be alone, Seung-hyun somehow found her and confessed his feelings for her.
She tries hard to ignore Seung-hyun's romantic overtures but she finds herself opening up to him. But then...
Her ex-boyfriend Ho-nam appears in her life again. Ho-am is the very man who broke her heart by dumping her all of a sudden one day.
After returning from a meeting with Ho-nam, Kang-joo looks at her sister Byul and feels so weak and vulnerable.

Choi Seung-hyun (Fitness club owner & Soo-hee?s son) / actor Um Ki-joon
He's stubborn, hyperactive, and impatient. But that's what makes him charming.
He's a passionate lover but doesn't cling to the opposite sex and so girls come and go in his life like a revolving door.
But there is one woman whom he had deep feelings for. She's Kang-joo.
Kang-joo is the only person who doesn't see that he changed into a nicer and diligent person because of her when he used to be short-tempered and lazy.
With an undying lover towards her, he tries to win Kang-joo's heart...

Yoo Ho-nam (psychiatrist) / actor Kim Seung-soo
Kang-joo's high school sweetheart.
He is impeccable and always maintains his composure. He follows a strict routine.
But when he's around with kids, he becomes playful and relaxed.
Due to the failure of his father's business, he broke up with Kang-joo and left for America where he enrolled in medical school and became a doctor. He is engaged to Mi-ra, who is pretty and from an affluent family. She can also be blunt at times.
But then one fateful day, he meets Kang-joo again in a chance encounter.
He thought he had buried his past feelings for her in the deep recesses of his mind. When he learns that Kang-joo is a single mom, he feels a deep concern over her situation...

Na Mi-ra (Ho-nam?s fiancée & Daughter of Soo-hee?s friend) / actress Kim Jung-hwa
With her pretty looks and wealthy family background, she took ballet classes as a child, which gave her a great-looking figure. She?s bubbly and always smiling.
But she's very possessive and competitive about getting what she wants.
She majored in modern dance in college and to pursue her dreams of becoming a musical actress, she studied overseas in New York. But she only found disappointment in New York and spent most of her time infatuated with Ho-nam.
When Ho-nam returns to Korea to open his private practice, she follows him back and prepares for their wedding.
Since she was close to Choi Seung-hyun's family since she was a kid, she has a great friendship with Seung-hyun.