Ami, a backpacker from Japan who is four years older than high school student Jimmy, shows up at his part-time job. The two end up spending the summer working at the same store, but Jimmy gradually develops a faint crush on Ami. The two of them grew closer as they rode motorcycles together at night and went to the movies, but suddenly, Ami decided to return to Japan. Ami proposes her "one promise" to Jimmy, who can't sort out his feelings. As time passes, Jimmy visits his parents' house for the first time in a while and finds a postcard that Ami sent him 18 years ago when she returned to Japan. Jimmy's memories of his first love come back to him, and he takes his first solo trip to Japan to confront his past and examine his present. Jimmy rides the train while listening to songs that remind him of his memories with Ami, and he heads to her hometown. Will Jimmy be able to reunite with Ami?
Miyuki sees a dying puppy in the park. Both of her parents died in an accident, and she believes something that her grandmother told her. Her grandmother said if you make a wish during the last snowfall in winter that wish will come true. Miyuki then makes a wish for the puppy's recovery. At this time, Tae Oh passes by and sees Miyuki and the puppy. Tae Oh wants to study in South Korea to become a veterinarian. He treats the puppy and the puppy's health improves. Meanwhile, Miyuki and Tae Oh become attracted to each other by a mysterious power, but Miyuki's uncle sends her to Kyoto. 7 years later, Miyuki arrives back in Tokyo and meets Tae Oh. He is now a veterinarian. A conspiracy is hidden behind them.
Emilia, a Filipino who arrived in Japan with aspirations of becoming a model, coincidentally encounters Matsuyama Mirai, an aspiring photographer. Their connection deepens as they find themselves drawn to each other. Mirai, intent on immortalising their moments together, diligently captures their essence through the lens of his camera. However, an unexpected parting disrupts the flow of their narrative. Subsequently, the saga of these two individuals unfolds beyond the shores of Japan, traversing the vast sea to the Philippines, where their story takes on new dimensions.
Singer Hyeon Seok develops problems with his hearing (Menieres syndrome) and has to stop his recordings. He notices a picture of Hokkaido in a magazine and decides to travel there. He eventually arrives in a a small village in Hokkaido for rest. While there, he reminisces about the old days. The owner of the inn offers him a Japanese meal. There he meets a bright cheerful girl named Megumi.
Despite losing her parents at age three in a car accident, Toko experiences an idyllic childhood thanks to her uncle, who raises her. She dreams of becoming an actress and, having had some local notoriety in her town, she is ready to take a leap of faith and travel to Tokyo to audition. But, as fate would have it, her hopes are dashed as her world and her country are turned upside down when Japan is struck by the Great East Japan Earthquake on March 11, 2011. This motivates Toko to assist with aid efforts in Kesennuma where she meets volunteer organizer Kiyotaka. While she initially senses something about Kiyotaka is amiss in the midst of their devastated surroundings, feelings of hope grow as do their feelings for one another.
Saeko is in a romantic relationship with Yusuke. Her boyfriend proposes to her, but, on that same day, he gets into a car accident and dies. Saeko falls into deep despair after his death. A few months later, she meets a man named Naruse. Although unaware at the time, Naruse received a heart transplant from Yusuke and he feels something for Saeko in his heart.
33-year old Han Je In is a mystery novelist who is notorious for habitual false reporting to the police in town. Her only friend is police officer Rok Hwan, who has had a crush on her since childhood. One day, Je In hears a scream of help from an apartment upstairs and reports that a serial killer lives above her but no one believes her. Convinced that Jason, the handsome man living upstairs, is a serial killer, she asks Rok Hwan to help follow him around with her. But as she learns more about Jason in her pursuit to uncover the truth, she begins to fall for him. Seeing her in this state, Rok Hwan feels a tinge of jealousy.
Mika goes all the way to Seoul to see her sweetheart Hyeong Jun who's been waiting for her. She suffers faints at the airport and she mistakes Kim Gyeon as Hyeong Jun due to trauma. Kim Gyeon also ends up falling in love with her, thus disrupting the balance between the three. Their memories start intertwining, but, before long, a tragedy occurs
Love comes in all flavors. Secret Ingredient is the story of a Korean man who gives up his entire luxurious life in Seoul in search of his childhood girlfriend, someone he’s never forgotten all these years, in the hopes that she would fall in love with him, not for who they were back then or who they are now, but for what they can aspire to be: happy, fulfilled and blissfully in love with one another.
Woo Hyun is a Korean man, and Haruka is a Japanese woman. They live different lives, but they both carry emotional scars from their first love. While looking for answers and hope, their fateful encounter will change their lives. It started with one message… Haruka, a stage actress in Seoul, has been in a slump ever since she broke up with her first love. She cannot forget him and keeps sending messages that go unread on LINE. Despite her emotional hurt, Haruka wants to believe in love. In Tokyo, Woo Hyun, an aspiring movie director, keeps on doing interviews concerning “love”. After being deeply hurt by his girlfriend, who thought about getting married, he no longer believes in love. Haruka and Woo Hyun have both grown timid of love. The two of them, who live apart in Tokyo and Seoul, have a chance encounter because of a LINE message delivered to Woo Hyun’s smartphone from Haruka. They exchange messages without knowing each other’s faces and are drawn to each other before they realise it
On a spring day Munakata Ikujou visited an old temple to view a 1000 years old sakura tree. There Ikujou discovered a 3-year-old girl and adopted her as his own daughter. 16 years later, Sakurako has grown up to become a beautiful woman. Sakurako then has a fateful meeting with Takanashi Hiroto. Their pure love begin.
Left alone on a trip to Hong Kong, Tomoko, a sales woman from Japan finds herself the victim of a purse-snatching. The police arrest the man she points out, but it turns out to be the wrong person: a young Korean man named Ji Hoon. Despite his anger and humiliation, he takes her out to dinner since she has lost all her money, and in return, she agrees to model for his amateur film. What follows is a magical and romantic two days. Upon returning to their respective countries, Tomoko must return to her nine-to-five job and Ji Hoon must resume studying to join the family business rather than pursuing his dream of becoming a film director. But soon the two begin to email each other and rekindle their relationship despite the distance and obstacles between them. Marking the very first time in television history that a drama has been co-produced between Japan and South Korea, the story shows us that love has no borders.
