Su-jeong, 19, has been living a hectic life, taking care of her deceased mother's belongings. She meets her first love, 'Black Flame Dragon', in a game she started by chance. However, her first love, which was full of excitement, ends up being the darkest part of her life... 16 years later, Su-jeong, who has become the team leader of Yongseong Department Store, meets the newly appointed head of the headquarters, Ju-yeon.

Su-jeong tries to repair her relationship with Ju-yeon, which was wrong from the start, but it is not easy. Su-jeong is just a thorn in Ju-yeon's side, who has a secret he does not want to be found out. Then, Ju-yeon eventually finds out about his private life and the situation changes.

A large-scale renewal project for Yongseong Department Store is underway, led by Joo-yeon. Joo-yeon and Soo-jeong grow closer as they work together. Joo-yeon's heart also opens up as Soo-jeong begins to understand him. But something happens that disappoints Joo-yeon in Soo-jeong.

Eventually, the 'Secret Room' opens. Soo-jung suddenly receives help from Joo-yeon. Joo-yeon's new appearance makes her laugh... Meanwhile, Shin-won does something he's never done before because of Ha-jin.

Ha-jin witnesses Su-jeong and Ju-yeon together. They must be separated before they realize each other's identity. Ha-jin's sabotage operation even involves Shin-won! Ju-yeon misunderstands that Su-jeong is interested in Shin-won...

Why on earth did they kiss? Soo-jung is embarrassed by what happened last night. She believes that Joo-yeon will confess or explain, but Joo-yeon doesn't say anything. Soo-jung, who is upset, decides to go on a blind date with Ha-jin.

Juyeon doesn't hide his feelings for Sujeong. However, Sujeong rejects him due to the 'younger man' trauma. Then Juyeon is about to get caught by Hyoseon.

Soo-jung and Joo-yeon finally confirm each other's feelings, and their thrilling secret love begins. It's a love that must be kept secret from everyone, but they're happy that they can be together... What is this ominous feeling? Meanwhile, Shin-won and Ha-jin have a chance meeting at a wedding hall

Strawberry and Black Flame Dragon meet again. As past wounds resurface, the conflict between Soo-jeong and Joo-yeon deepens. It seems like this is the end... but to make matters worse, a scandal breaks out between the two.

Joo-yeon is fired. In the end, he is abandoned by Hyo-sun and becomes alone. Soo-jeong hides the crisis that is in front of her and tries hard for Joo-yeon. Meanwhile, Ha-jin's ex-husband comes to see him.

Soo-jeong, who lived alone, shouldering everything in order to be recognized and not be ignored. Joo-yeon, who wanted to be loved by her grandmother even while hiding herself. Can the two of them release their respective seals and be together?

Su Jang turns down an offer to work in the U.S., choosing to stay with Ju Yan, and they receive their happily-ever-after as they are appointed to key positions at Yongsung Department Store. Ju Yan's grandmother, Chairwoman Jang, apologizes to him for her past behavior, and Hyo Seon also makes peace with Ju Yan, leading to a full reconciliation.