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.
Based on a Japanese manga, Kanna-San, Daiseikou Desu, this story revolves around Kang Han-na, an overweight phone sex employee and secret vocalist for Ammy, a famous Korean pop singer who actually lip syncs as she cannot sing. After getting humilitated publicly by an ungrateful Ammy, Han-na undergoes an extreme makeover to become a pop sensation herself.
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.
Beautiful, workaholic Bo-hee is a successful marketing executive at the number one toy company in Korea. Respected by her colleagues and in line for a promotion, she makes an irrevocable mistake that gets her fired from her job. Bo-hee's life further spins out of control when her husband Gang-sung leaves her soon after. Bo-hee is befriended by her neighbor Nan-hee, an amateur sex expert who runs a sex shop on the brink of bankruptcy called "Casa Amor." Nan-hee's predicament inspires Bo-hee's creativity, and using her background in children's toys, she is determined to save the shop by making its ambiance more refined and by promoting better sex toys.
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?
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.
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.
Ryoko Matsumura is a popular writer in her 50's. She also knows that she has Alzheimer’s. Ryoko Matsumura begins to teach at a university. She meets a young Korean man in his 20's. They become attracted to each other.
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.
The probability of a couple that had broken up getting back together and having a successful relationship is just 3%. Dong-hee and Young, who had broken up over a minor tiff, later realize their love for each other and end up getting back together. But will they be able to fit into the 3% bracket?
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.
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.
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.
Miso lives from day to day by housekeeping. Cigarettes and whiskey are the two things that get her through the day. As cigarette prices and rent start to rise, Miso decides to give up her house for cigarettes and whiskey, leading her to couch surf with old friends while reconsidering her place in life.
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.
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.