Cellphone app Joalarm is created. If someone likes you and they are within 10 meters of you, the alarm for the app rings. The app also shows how many people like you, but the app doesn't reveal specific details on who likes you.
Kim Jo-Jo (Kim So-Hyun) is a high school student. She is pretty and smart. She seems like cheerful person, but her parents died when she was young. Since the death of her parents, Kim Jo-Jo has lived with aunt's family. Living there is not easy for Kim Jo-Jo. She doesn't download the app Joalarm.
Meanwhile, Hwang Sun-O is a popular male student at the same high school where Kim Jo-Jo attends. He is the son of a wealthy family, but he is not loved by his parents. His best friend Lee Hye-Young also attends the same high school. Hwang Sun-O notices that his best friend Lee Hye-Young likes Kim Jo-Jo. Hwang Sun-O wants to know if his friend really likes her, so he kisses her.
Lee Jae-Sang (Rain) is a lawyer at JK Law Firm, which is one of the biggest law firms in South Korea. He is an excellent lawyer, but he only cares about winning for his benefit. One day, he has a mysterious car accident and he is drawn into a parallel world. There, Lee Jae-Sang finds himself working as a prosecutor. He is strict in carrying out the law. He is married to Ra Shi-On (Lim Ji-Yeon), who loves Lee Jae-Sang and is faithful to him. In the world where Lee Jae-Sang came from, he broke up with Ra Shi-On ten years earlier and Ra Shi-On works as a detective. Lee Jae-Sang struggles to cope with his different selves.
Hotel Del Luna ini merupakan sebuah hotel seperti hotel pada umumnya. Yang membedakan hotel yang terletak di kota Seoul ini dengan hotel lainnya ialah costumer mereka yang semuanya adalah hantu.
Dan dari tempat inilah 2 makhluk bertemu, dimana Jang Man Wol (IU) merupakan seorang CEO dari hotel tersebut yang terjebak karena sebuah kesalahan besar dan mengakibatkan dirinya terjebak begitu lama di hotel tersebut.
Namun ia tidak menyangka bahwa dirinya bertemu dengan seorang pria yang mengalami sebuah peristiwa tertentu, lalu menjadi manajer di hotel tersebut.
Mo Seok-hee is an only child and her father runs the large company MC Group. She is beautiful, smart and rich. Mo Seok-hee appears like she is arrogant, but she struggles over her mother’s death. Her mother was killed 15 years ago. Meanwhile, Heo Yoon-do is a lawyer, but he doesn’t even have an office. He solves small problems of neighborhood residents at a restaurant. He is full of love. Miraculously, Heo Yoon-do is headhunted to join the TOP team at MC Group. The TOP team manages the affairs of the family who runs the MC Group. Their job includes covering up immoral or illegal behaviors done by the family.
Moon Suk-Goo works as a manager at Cheonrima Mart, which belongs to the Daema Group. Cheonrima Mart's future looks bleak as they don't have many customers and Moon Suk-Goo is frustrated by the store's situation. One day, Jung Bok-Dong, who was an executive at Cheonrima Group, is demoted to the CEO position at Cheonrima Mart. Manager Moon Suk-Goo begins to have hope that the store will experience a turnaround with the new CEO. In actuality, Jung Bok-Dong wants to destroy Cheonrima Mart to take revenge on the parent company for his demotion. Unexpectedly, Jung Bok-Dong's actions soon causes the store to attract customers.
Wie Dae-Han (Song Seung-Heon) is an ex-lawmaker and is a materialistic kind of politician. He wants to get elected as lawmaker again. One day, 18-year-old girl Da-Jung (Roh Jeong-Eui) comes to him. She tells him that he is her real father. Her mother raised four children, including Da-Jung, alone, but she died in a hit-and-run accident. Da-Jung is the only one now taking care of her 3 younger siblings. Wie Dae-Han accepts Da-Jung and her 3 younger siblings. He carries out “The Great Show” to become a lawmaker again.
Semua orang akan berjuang apapun demi masa depan mereka dan memiliki kehidupan yang layak, mungkin begitu gambarannya dari para pemain “Level” Up ini yang berjuang demi perusahaan pengembangan game online.
Ahn Dan Te (Sung Hoon), seorang pria yang ahli Restrukturisasi yang memiliki kepribadian yang sangat Perfeksionis dan dingin dikirim dari perusahaan game pusat untuk menyelematkan perusahaan tersebut
Dan dirinya dipertemukan dengan Shin Yun Hwa (Han Bo Reum), yakni kepala dari pengembangan game perusahaan yang hampir bangkrut. Ia sangat menyukai game. Namun, disinilah awal cerita mereka.