Protect the Boss

Loan shark (ep. 1)

Chairman Cha Bong-man, Ji-heon's father

Secretary Jang's blind date (ep. 18)

Cha Ji-heon: A spoiled heir of DN group, known to be immature and hold grudges. He quickly falls in love his secretary, Noh Eun-seol though the latter is initially confused and not accepting of his advances. They date then eventually get married after a series of comedic events at the end of the series.

Cha Mu-won: The less spoiled heir and cousin of Cha Ji-Heon. He had conflicts with his mother regarding Seo Na-yoon whom he ends up with the latter his mother had an rivalry with Na-yoon's mother at the near end of his series. Known to be sarcastic and mysterious, he ends up greatly caring for Na-yoon as she is his first love with whom he loved when she was dating Cha Ji-Heon leading Na-yoon to be torn with Cha Mu Won and Cha Ji Heon though she ends up chasing Cha Mu Won when he seems to be attracted to Noh Eun Seol. Cha Mu won quickly develops an attraction to Noh Eun sol after Seo Na yoon rejects him due to her not wanting to make the same mistake once again. He ends up with Seo Na Yoon whom he had always loved. At the end of the series, both Mu won and Na yoon remain unmarried. Though he has proposed to her and Na yoon wants to get married, he thinks she should "grow up" a bit more.

Seo Na-Yoon: Ji-heon's previous girlfriend and Mu won's first love. Initially seeming like a spoiled rich brat, Na-Yoon is eventually revealed to care deeply and stand by the people she gets close to. She is seen to cry and be emotional with Cha Mu Won the only person who she actually truly cry around and depend on, whom she ends up with. She deeply loved and cared about both Cha Ji Heon and Cha Mu Won though she is both their ex girlfriend and due to her mistake which is not revealed in the series ends up leaving Cha Ji Heon she comes to back win over Cha Ji Heon but due to Cha Ji Heon being interested in Noh Eun Sol, she realizes her attraction and love towards Cha Mu Won who both have issues due to the treatment of both of their mothers, she ends up trying to win over Cha Mu Won in which she does win in after rejecting him. She is known to be playful when becoming friends with Noh Eun Seol in the series with whom she was originally not on exemplary terms with, she ends up moving in with Eun Seol when she becomes friends with her. In the end, she wants to marry Cha Mu Won but he thinks she needs to "grow up" a bit more. She has also been described as adorable and is weirdly loveable.