History Series / SomedayOrOneDay

* DisabledLoveInterest: Jun Jie, who has impaired hearing, has a crush on Yun Ru and the promotional material sets him up as a competitor against Zi Wei. In the series, he confesses to her early on but she doesn't reciprocate, and he doesn't fall for Yu Xuan in Yun Ru's body.

* SurprisinglyGoodEnglish: The opening song is sung entirely in grammatically correct English.

* {{Bowdlerise}}: The Mainland Chinese broadcast excised all scenes related to sexuality [[spoiler: such as the real Quan Sheng's [[{{Gayngst}} entire backstory]]]] and a [[ADateWithRosiePalms scene where a character masturbates]]. They also censored elements that showed Taiwan as an independent country (like flags and identification documents).

* ADateWithRosiePalms: [[spoiler: Zhi Qi, in his brother's body,]] masturbates while looking [[spoiler: at pictures of Yun Ru.]]

* AnguishedDeclarationOfLove: Jun Jie confesses his feelings to Yun Ru in his attempt of [[spoiler: TalkingDownTheSuicidal, when she is convinced no one cares about the real Yun Ru, only Yu Xuan.]]

* AnguishedDeclarationOfLove: Jun Jie does this in his attempt of [[spoiler: TalkingDownTheSuicidal Yun Ru, when she is convinced no one cares about the real Yun Ru, only Yu Xuan.]]

* ADateWithRosiePalms: [[spoiler: Zhi Qi, in his brother's body,]] does this while looking [[spoiler: at pictures of Yun Ru.]]

* SkywardScream: Jun Jie does this [[spoiler: when holding Yun Ru's corpse.]]

* IdentityBreakdown: The [[spoiler: real Yun Ru, upon seeing how popular she becomes when Yu Xuan is possessing her, and that her crush Zi Wei adores Yu Xuan, decides to take on that personality, since by her reasoning they only care about Yu Xuan.]] Sadly it doesn't work as the people around [[spoiler: her note that she acts like a different person. Zi Wei is turned off and suspects that Yun Ru has returned to her body. They then express that the way she was before was much preferable to the real Yun Ru. This is a major factor leading to Yun Ru's death.]]

* BittersweetEnding: [[spoiler: Xie Zhong Ru/Xie Zhi Qi is stopped from causing harm,]] but once this is done [[spoiler: Li Zi Wei, Huang Yu Xuan, Mo Jun Jie, Chen Yun Ru, and many others lose their memories of the series' events. The Zi Wei and Yu Xuan that time traveled end up being RetGone,]] though there is the possibility of [[spoiler: Yu Xuan the little girl and Zi Wei the student meeting each other after growing up.]]

* CosmicRetcon: By [[spoiler: breaking the casette of Wu Bai's "The End of Love"]] in the past, this means that [[spoiler: Zhi Qi is unable to go back in time, therefore preventing Yun Ru, Jun Jie, Zi Wei, and presumably Wen Rou's deaths. However, this means that no MentalTimeTravel happens, and Quan Sheng and Yu Xuan never meet (and Quan Sheng [[AmbiguousSituation may have actually died]]). Everyone loses all their memories of the story's events and the Yu Xuan and Zi Wei that engaged in time traveling are RetGone.]]

* RippleEffectProofMemory: [[spoiler: The time travelers retain their memories of what happened in the loop. Though by the ending, [[CosmicRetcon this is no longer the case]] due to VictoryGuidedAmnesia.]]

* UncertainDoom: [[spoiler: Quan Sheng attempts suicide, but thanks to Zi Wei's consciousness entering his body, his body survives but no mention is made of his soul remaining trapped in the body unlike the explicit scenes of Yun Ru stuck inside and Zhong Ru's voice interrupting Zhi Qi. In the final episode when a CosmicRetcon undoes Zhi Qi's wrongdoing, preventing Yun Ru and Zi Wei's deaths, no mention is made of what happened to Quan Sheng.]]
* VictoryGuidedAmnesia: [[spoiler: The steps Zi Wei, Yu Xuan, and Jun Jie take to SetRightWhatOnceWentWrong involve a CosmicRetcon, therefore eliminating all memories of the series' events from everyone involved in the story.]]

* PsychoticSmirk:
** The first hint that Xie Zhong Ru [[spoiler: who is really Xie Zhi Qi]] is off are his sinister smiles [[StalkerWithACrush when looking at and hearing about Chen Yun Ru.]] Later on it turns into outright SlasherSmile territory [[spoiler: when he's attacking with intent to kill.]]
** [[spoiler: The real Yun Ru]] has a creepy TechnicallyASmile when [[spoiler: she regains control of her body, her IdentityBreakdown imminent.]]

* UncertainDoom: [[spoiler: Quan Sheng attempts suicide, but thanks to Zi Wei's consciousness entering his body, his body survives but no mention is made of his soul remaining trapped in the body unlike the explicit scenes of Yun Ru stuck inside and Zhong Ru's voice interrupting Zhi Qi. In the final episode when the ResetButton is pushed, no mention is made of what happened to him.]]

* ReadingLips: Jun Jie does this in the final episode [[spoiler: when observing Yun Ru talk to herself (really talking to Yu Xuan trapped in her body). He manages to accurately understand the entire conversation.]]

* AgeGapRomance: Without getting into the time travel shenanigans, [[spoiler: Zi Wei and Yu Xuan have a 12 year age difference.]]

* AlasPoorVillain: [[spoiler: Cai Wen Rou is jealous of Yu Xuan/Yun Ru since Zi Wei likes her. To humiliate her, she plasters pictures of Yun Ru changing for gym class on the school bulletin board. However, her death at Zhong Ru's]] hands is played for all its terrifying potential.

* AttentionWhore: Not in the usual way. [[spoiler: Yun Ru has never gone through with suicide since everyone would think her pitiful and forget her.]] But after she sees [[spoiler: how popular she became when Yu Xuan controlled her and Zi Wei fall in love with Yu Xuan,]] she decides to go through with it, assured at that point that more people would react differently.

* BigBad: [[spoiler: PsychoPsychologist Xie Zhi Qi]] is the only major antagonist, directly responsible for [[spoiler: murdering Cai Wen Rou and Li Zi Wei, attacks Yun Ru with intent to kill, and being (one of) the causes of the StableTimeLoop.]]

* {{Bowdlerise}}: The Mainland Chinese broadcast excised all scenes related to sexuality [[spoiler: such as the real Quan Sheng's entire backstory]] and the ADateWithRosiePalms scene and censored elements that showed Taiwan as an independent country (like flags and identification documents).
* BuryYourGays: [[spoiler: Quan Sheng's body is lost in the plane crash (Zi Wei's mind travels back in time). That coupled with the [[UncertainDoom possible loss of his personality]] in his GayngstInducedSuicide may make him one of the few people in the series to stay dead.]]
* ChekhovsGunman: Remember [[spoiler: that psychologist who shows up once]] in an early episode? [[spoiler: He's related to the guy who is unhealthily obsessed with Yun Ru and may have murdered her. And he's also the BigBad responsible for killing three people.]]
* CoolUncle: Chen Yun Ru's uncle encourages her, acts concerned for her welfare, and takes the reveal of Yu Xuan possessing her well, to the point where he acts like a better father figure to her than her actual father.

* DarkestHour: In the last few episodes, [[spoiler: Zhi Qi is intent on killing Yun Ru, has killed the present Zi Wei, and breaks the Walkman to prevent the heroes time traveling. Yun Ru has a crisis of identity, and the repaired-but-barely-working Walkman runs out of its final play as Yu Xuan fails to change or prevent anything.]]

* DeathOfPersonality: Unlike Chen Yun Ru whose soul is explicitly shown as stuck inside her body, [[spoiler: the absence of such scenes for Quan Sheng may mean that the real one is effectively dead once Zi Wei takes over.]]
* DisabledLoveInterest: Mo Jun Jie, who has impaired hearing, has a crush on Chen Yun Ru and the promotional material sets him up as a competitor against Li Zi Wei. In the series, he confesses to her early on but she doesn't reciprocate, and he doesn't fall for Huang Yu Xuan in Yun Ru's body. [[spoiler: Though with the MaybeEverAfter he gets with Yun Ru in the ending, this may come into play again.]]
* DisappearedDad: Yun Ru's father shows up only once after she is released from the hospital. Due to the divorce proceedings, he never shows up in the narrative again even during situations when it would make sense [[spoiler: like visiting her grave, which her mom and brother do.]]

* FatBestFriend: Kun Bu, Yu Xuan's best friend (who is also the only overweight character in the series) is an outgoing GenkiGirl who gives Yu Xuan some leads early on but is largely non-essential to the plot.

** [[spoiler: Zhong Ru attempts to resist Zhi Qi (who is inhabiting his body) from murdering Yun Ru, which stuns him for a moment.]]

* {{Gayngst}}: The [[spoiler: real Wang Quan Sheng faced homophobic bullying from his peers and his crush when confessing his feelings goes wrong.]]
* GayngstInducedSuicide: The [[spoiler: real Quan Sheng [[SuicideBySea walks into the sea]] after his crush rejects him and participated in homophobic bullying, although his body survives but gets taken over by Zi Wei.]]

* IdentityBreakdown: The [[spoiler: real Yun Ru, upon seeing how popular she becomes when Yu Xuan is possessing her, and that her crush Zi Wei adores Yu Xuan, decides to take on that personality, since by her reasoning they only care about Yu Xuan.]] Sadly it doesn't work as the people around [[spoiler: her note that she acts like a different person and Zi Wei is turned off and suspects that Yun Ru has returned to her body. Both express that the way she was before (when Yu Xuan was possessing her) was much preferable to the real Yun Ru. This is a major factor leading to Yun Ru's death.]]
* InterruptedSuicide: [[spoiler: Jun Jie attempts to stop Yun Ru from committing suicide. In the first iterations of the time loop he fails but in Yu Xuan's last ditch effort to travel back in time to Yun Ru's body he pulls her back.]]

* MaybeEverAfter: The ending conveniently [[spoiler: takes Li Zi Wei out of the equation in the Chen Yun Ru - Mo Jun Jie - Li Zi Wei]] LoveTriangle and makes the remaining two people friendlier though doesn't definitively confirm any romantic feelings on [[spoiler: Chen Yun Ru's part]].
* MentalTimeTravel: By listening to an old Walkman that plays Wu Bai's "Last Dance," Huang Yu Xuan's consciousness goes from 2019 to 1998, and lands her in Chen Yun Ru's body. [[spoiler: Li Zi Wei's consciousness goes from 2003 to 2010 and lands him in Wang Quan Sheng's body in the same manner, and he travels from 2017 back to 2003 in the plane accident.]] Time still passes in the 'base' times and the bodies left behind are left in a vegetative state. [[spoiler: Though when Xie Zhi Qi uses the Walkman, he is able to be woken up by outside stimulus.]]

* MiscarriageOfJustice: [[spoiler: Jun Jie]] goes to prison for [[spoiler: Yun Ru's murder (which was really a suicide, and not in the SuicideByCop manner).]]

* NeverTheSelvesShallMeet: [[spoiler: Zhi Qi, in Zhong Ru's body, talks to his younger self and encourages his [[InsaneEqualsViolent unstable tendencies,]] which lead him to grow up, go back in time to his brother's body, murder people, and [[StableTimeLoop encourage his younger self, and so on...]]]]

* ReadingLips: Jun Jie does this in the final episode [[spoiler: when observing Yun Ru talk to herself (really talking to Yu Xuan trapped in her body).]]

** [[spoiler: Xie Zhi Qi is the [[FamilialBodySnatcher one behind Zhong Ru's actions.]]]]

* ShooOutTheClowns: After [[KnightOfCerebus Zhong Ru's appearance]], Yu Xuan's friends steadily make fewer appearances and eventually stop appearing in the plot.

* StableTimeLoop: It's not until [[spoiler: multiple loops of trying to change the past but failing and Zi Wei saying what will happen to his past self in Quan Sheng's body in the plane to Shanghai that he realizes he's repeating the same words that were said to him when he was in Quan Sheng's body. Though the minute differences in Quan Sheng's reaction and his hope that Yu Xuan could change what happened give him a bit of hope.]]

** Furthermore, [[spoiler: Zhi Qi in Zhong Ru's body influences the Zhi Qi of the past by encouraging his budding sociopathic tendencies and obsession with Yun Ru and having him witness Wen Rou's murder.]]

* SuicideByCop: [[spoiler: Yun Ru in her IdentityBreakdown doesn't try to avoid Zhi Qi following her and offers no resistance when he tries to murder her. When Zhi Qi is interrupted by the police capturing his body in 2019, she tries to get Zhong Ru and later Jun Jie to kill her. When they refuse, she takes matters into her own hands.]]

* UncertainDoom: [[spoiler: Quan Sheng attempts suicide, but thanks to Zi Wei's consciousness entering his body, his body survives but no mention is made of his soul remaining trapped in the body afterwards unlike the explicit scenes of Yun Ru stuck inside and Zhong Ru's voice interrupting Zhi Qi, possibly indicating that his consciousness is no longer present. In the final episode when the ResetButton is pushed, no mention is made of what happened to him.]]

[[caption-width-right:350:[[{{Tagline}} The Mystery of Love]][[note]]from bottom to top: Chen Yun Ru, Li Zi Wei, Mo Jun Jie[[/note]]]]

* MyFutureSelfAndMe: [[spoiler: Both meetings of the selves end up fueling the StableTimeLoop.]]
** [[spoiler: The OlderAndWiser, grizzled time traveler Zi Wei and Li Zi Wei in Quan Sheng's body meet before the plane flight that will kill Quan Sheng and lead Zi Wei to travel back in time.]]