Hanna, an overweight lip-sync artist who ghost sings for Ammy, a known pop diva, secretly likes Han Sang-jun. When Ammy humiliates Hanna in Han's presence, Hanna decides to undergo a cosmetic surgery.
Along with his young son, Ji-ho, Woo-jin misses his wife Soo-a, who died after promising to return a year later with the rainy season. Miraculously, they reunite with Soo-a when the rainy season comes around, but she has no memory of her husband and son whom she dearly loved.
In the year 1999, a young woman leaves her quaint seaside house and returns to the city, leaving in the mailbox a card for the next owner, with instructions to forward any mail of hers to the new address. In the year 1997, a jaded young architect moves into the same house and finds the letter. His reply, which he slips into the mailbox, finds its way to her, beginning a parallel-time love story separated by a span of two years.
When Seung-min was on his first year at the Academy of Architecture, he met Seo-yeon. She was a musician student, and Seung-min totally fell in love with her. Years have passed, and now he meets Seo-yeon again - she asks him to rebuild her father's old house.
Hong Seol, a student from a poor family, meets a rich Yoo Jung, who is her senior at her university. They both develop a rather inconvenient relationship after knowing each other.
Jin-hyeok opens a cake shop in an old antique shop, hiring Seon-woo, Korea's best pastry chef, who fell in love with him in high school. Also there, are Su-young, crushing on Seon-woo, ex-boxer Ki-beom, and Seon-woo's French ex-boyfriend.
Young-seok, who feels overwhelmed and lonely in what should be his glorious youth, meets a woman who introduces herself as Josée, and they share a once-in-a-lifetime romance.
An assistant to a TV producer, eager to stay off his bad side, promises to convince her former professor, a famous but reclusive academic, to appear on their show, which helps locate long-lost persons. Who does grey-haired Professor Yun Suk-Young want to see again more than anything? The answer to that question lies decades in the past.
Four different couples have a romantic week over New Year's Eve. Both coming out of failed marriages, Ji-ho and Hyo-young are not open to the possibility of new love, while Jin-ah heads to the other side of globe and encounters Jae-hun.
Lee Hyeong is a talented songwriter. He happens to connect people who are not good with love. Those include Hyeong-Gyeong who wants to become a singer, but she suffers from stage fright. Scully is a high school student. She helps Lee Hyeong's spirit. Chan-Young is a colleague of Lee Hyeong and he likes Hyeong-Gyeong, but in vain.
After a trivial quarrel, co-workers Dong-hee and Young decide to take a break from their relationship. But they realise that they still love each other as their attempts to find new partners fail.
Chul-soo is the only son of a legendary thief family. He falls in love with Young-hee who is a police officer. Her family is also a police family. To get her parents’ permission to marry, Chul-soo undertakes an exam to become a police officer, but both families work to prevent their marriage.
One day, during a university festival where people are often known to find a partner, the 3 incredibly single members of the robot club decide to attend. There the sloppy and timid Hwi-so meets a very aggressive girl by the name of Hye-jin. His romantic advances, which he learned through reading books and watching YouTube, finally wake up to make their move. But will two finally become one this fall?
Kang Woo-ram is busy preparing to get a job. Lee Hyun-ji is a would-be anchor, but she works at a homemade hamburger restaurant. One night, Woo-ram visits the hamburger restaurant and orders a double patty hamburger, which has a "buy one, get one free" sale. This is how their relationship begins.
Je-In is a mystery novel writer. She chases after a serial killer with her longtime friend Rok-Hwan. Rok-Hwan is a detective. A handsome and mysterious man, Jason, appears in front of them.
Seung-jin, who is preparing for an audition to pursue his ambition of becoming a singer, moves into a new studio apartment. On the first night, as he just started to settle in, he hears a woman wailing from next door. With all the noise she makes owing to her badly soundproofed room, La-ni has driven away several neighbors. Seung-jin isn't one to back down easily. Their argument intensifies to the point that they have discovered everything about one other's life through their noises save for their names and faces.
Hà Mi is a young musician that has a great passion for composing music. G-Feel - a genius musician of Korea, who is facing with the pressure from his fame. Between two strangers, living in two countries, there's a special bond that is Yoon Hee. The story about that speical relationship between them is revealed when G-Feel decides to travel to Vietnam after an incident.