Someday or One Day

Huang Yu Xian lost her boyfriend from a plane incident two years ago. She misses him a lot and sends messages with no reply. Meanwhile, her colleague claims there is an app that can find someone who looks identical to you.

Huang Yu Xuan is shocked to find out that her boyfriend was planning to propose to her. Meanwhile, through Ah Tuo's app, she finds a photo that has a woman who looks exactly like her and her boyfriend is beside the woman.

Going to the past year, 17-year-old Chen Yun Ru meets her school friends Li Zi Wei and Mo Jun-Jie. Back to the present, Huang Yu Xuan is disappointed to find out that the man in the photo is not her boyfriend.

In 1998, Chen Yun Ru is unconscious in the hospital after a stranger's attack. Meanwhile, in the present, Huang Yu Xuan falls asleep listening to an old tape and wakes up, becoming Chen Yun Ru.

Chen Yun Ru thinks her being Huang Yu Xuan was all a dream. Meanwhile, Chen Yun Ru, Li Zi Wei and Mo Jun Jie try to find the attacker.

Huang Yu Xuan finds herself back in 2019, and although she goes to a mental hospital, the doctor does not believe her. Meanwhile, she receives Chen Yun Ru's diary from the 32 Cafe's owner.

Huang Yu Xuan prepares to go to Shanghai, but first she decides to go to the past once again; she finds out that Li Zi Wei and Wang Quan Sheng are different people, and she becomes confused that they look the same.

Mo Jun Jie is accused of being the suspect in the attack of Chen Yun Ru, but they go to the police to prove he is innocent; Chen Yun Ru goes to her uncle to tell him she is Huang Yu Xuan, but he does not believe her.

Everyone is surprised to see Chen Yun Ru being so extroverted; Li Zi Wei feels jealous to see Mo Jun Jie and Chen Yun Ru become so close.

Li Zi Wei encounters a lost girl, and he escorts her home safely; she tells him her name is Huang Yu Xuan and to never forget her; Li Zi Wei finds himself falling in love with Chen Yun Ru.