- Title: 海派甜心 / Hai Pai Tian Xin
- English title: Hi My Sweetheart
- Also known as: Play Boy and Sweetheart / Shanghai Sweetheart
- Genre: Romance, comedy
- Show Lo as Xue Hai / Lin Da Lang 薛海 / 林達浪
- Rainie Yang as Chen Bao Zhu 陳寶茱
- Lee Wei as He Yan Feng 何言風
- Maggie Wu as Mo Li 莫莉
- Nikki Deng (邵庭/鄧紹婷) as Wang Ye Qian 王野倩
- Zhang Yi Mei (張怡美/娜娜) as Li Jia Jia 李佳佳
- Fang Fang (方芳) as Xue Bo 薛波
- Xiang Yu Jie (向語潔) as Xue Pei 薛沛
- Wang Yue as Wang Yu Lan 王玉蘭
- Wen Shuai (文帥) as Chen Run Fa 陳潤發
- Jiang Qi Lin (江奇霖/七零) as Ba Shuang 巴雙
- Liu Rui (劉銳/虎虎) as Wu Ke 伍科
- Chen Bi Wei (陳筆威) as Gao Gang 高剛
- Yin Chong Zhen (尹崇珍) as Hui Min 慧敏
- Shi Zhen Long (史振龍) as A Gen 阿根
- Xie Li Jin (謝麗金)
- Chocolate Lai (賴亭君)
Xue Hai (Show Luo) was a certifiable dork who comes from a very wealthy family and has been protected by his oldest sister since young, until he is 20 years old. One day, he decided to move out of his comfort zone and study abroad in Hangzhou. To protect his true identity, Xue Hai's oldest sister, Xue Bo, gave him the alias of Lin Da Lang, who was a supposedly poor student.
In his new university, Da Lang meets Chen Bao Zhu (Rainie Yang), who protects him from bullies who tease him for being a dork. In return, Da Lang promises to be Bao Zhu's close friend and eventually, they fell in love with each other. During this time, Bao Zhu's father goes bankrupt, flees, and left her and her mother behind. Using Bao Zhu's father as an example of failure, Bao Zhu's mother forces Bao Zhu to date someone wealthier, and break up with Da Lang. On the day of her birthday, something happened to Bao Zhu that cause them to have a misunderstanding that expanded over years. Thinking that he got dumped by his first love, Xue Hai drops his alias as Da Lang.
Three years later, Xue Hai has transformed himself from a dork into a play-boy. After hearing Bao Zhu's familiar voice on the radio as a DJ, Xue Hai decides to seek revenge but true love can't be separated so after seeing her with her 'judo senior', he became jealous and later on realizes that he still loves her. But what will happen when she finds out his real identity? Will the misunderstanding be cleared up?