A man who can distinguish between the sounds of day and night, Park Do-kyeong, suddenly gains another supernatural ability-he can foresee the future, but only of one woman. Do-kyeong has never met her and doesn't even know who she is. Yet one day, he sees a vision of her calling off her wedding the day before the ceremony-and her name is Oh Hae-young.

Obnoxious' Hae-young tries to pretend she's fine and happy after her wedding is called off-but ends up causing accident after accident. Unable to handle her anymore, her parents decide to kick her out of the house. Now on her own, Hae-young faces single life head-on. And as it begins, she meets someone…

Hae-young's new home, a studio with no options, already has someone living in it. That person is none other than Do-kyeong. With only a thin wall between them, the two are forced to llive side by side. Do-kyeong tries to kick her out, but Hae-young insists she's never leaving! Just then, Do-kyeong sees a vision of Hae-young getting in trouble in the future.

The beautiful Oh Hae-young shows up as the team leader of the obnoxious Hae-young's team at work. The obnoxious Hae-young is reminded of her high school days and falls into a slump. As if that is not enough, Hae-young finds out that her supervisor, Soo-kyeong, is Do-kyeong's older sister. Meanwhile, a romance begins to bloom between Hae-young and Do-kyeong at home.

Hae-young runs toward Do-kyeong and gives him a huge hug-along with her pride, something else drops too. Full of laughter, the two begins to open up, and their relationship develops into one where they even share breakfast together.

Hae-young's mother begins to sense a romantic spark between her daughter and Do-kyeong. Meanwhile, Do-kyeong's mother runs into someone unexpected during a meeting with Chairman Jang. As time passes and Hae-young's birthday is coming up, Do-kyeong prepares something for her.

Hae-young prepares a gift for Do-kyeong in return for the standing lamp. The two nearly run into Soo-kyeong in the alley quickly hide together in the dark. It seems like everything is going well, but Do-kyeong receives an email from the beautiful Hae-young, and a man appears in front of the obnoxious Hae-young.

Hae-young breaks down after running into Tae-jin and cries in front of Do-kyeong, who quietly stays by her side. Meanwhile, as Jin-sang comforts Soo-kyeong, a secret from her past appears. Do-kyeong grows concerned of Hae-young as she does not return home, and eventually decides to visit her parents.

Tae-jin comes by to Hae-young. Afterward, Hae-young breaks down in tears over the truth behind their broken engagement. Meanwhile, Do-kyeong experiences another questionable vision and grows increasingly anxious as the vision continuously repeats. Between drunk Jin-sang and Soo-kyeong, a new chapter begins.

After the kiss, Hae-young receives no call from Do-kyeong. Hae-young tells herself that she will not fall for him again, but she can't help but miss him. Soo-kyeong feels her heart flutter for Jin-sang after 'that' night, but Jin-sang does not remember anything. During a fight, Hoon brings up Do-kyeong's childhood trauma, and after the argument, Do-kyeong leaves as the trauma resurfaces.

Tae-jin sees Do-kyeong and Hae-young together and punches Do-kyeong. Still having no idea about the night with Soo-kyeong, Jin-sang continues his carefree life, leaving Soo-kyeong frustrated. Meanwhile, after figuring out everything, Tae-jin goes to see Chairman Jang.

With everything weighing on her, Hae-young goes through a rough time. Do-kyeong also feels lost, not knowing how to approach her. Soo-kyeong has a clumsy moment on the bus, only to face an even more embarrassing incident ahead. Meanwhile, Do-kyeong has a vision of his death and makes some kind of decision.

Do-kyeong shows up at Hae-young's house, but she keeps her distance. While Hae-young tries to forget Do-kyeong and move on, Do-kyeong struggles to get over Hae-young. Then, something begins to change within him.

To see Hae-young, Do-kyeong asks Soo-kyeong for a favor that he has never asked before. Meanwhile, while Jin-sang and Soo-kyeong are having a meal together, Jin-sang's ladies from Monday to Saturday suddenly show up, putting him in a tough spot. Naturally, Soo-kyeong just leaves.

A future that cannot be changed, Do-kyeong feels anxious but chooses to love Hae-young with everything he has. Meanwhile, Jin-sang struggles to face Soo-kyeong after she tells him she is pregnant. Soo-kyeong gives him one last suggestion. At last, Do-kyeong sees the driver of the car that hits him in his vision.

Do-kyeong starts making moves on Hae-young; a surprise gift at the office gives her butterflies. Soo-kyeong and Jin-sang are now facing a serious life decision, but Jin-sang is not ready. Tae-jin, full of anger, makes a decision after much thought.

Do-kyeong invites Hae-young to a dinner with his family, where she makes a bornshell announcement. Jin-sang leaves Soo-kyeong and tries to return to his life-until someone unexpected appears. Meanwhile, a completely drunk Tae-jin heads off somewhere, and Do-kyeong uncovers another clue related to his foretold death.

Hae-young moves into Do-kyeong's place. Soo-kyeong and Jin-sang begin their love in reverse. Tae-jin and the beautiful Oh Hae-young leave the past and move on. Just as Do-kyeong prepares to propose to Hae-young, something unexpected happens!