* CrowningMomentOfHeartwarming: ''Moon Viewing Recital'' as a whole. Especially considering it came after many really [[TearJerker depressing songs.]] [[ManicPixieDreamGirl Momo's]] interactions with [[DeadpanSnarker Hibiya]] are all too cute, and it's nice to watch Momo help Hibiya slowly get over his SurvivorGuilt was very nice to watch. [[AwLookTheyReallyDoLoveEachother Shintarou watching out for Momo at the end made it sweeter.]]
** ''Summertime Record'', and the fandom's response to it. [[spoiler: Ayano would be proud.]]
* EnsembleDarkhorse:
** [[TheMessiah Ayano]], who was already pretty popular way back when she was first introduced in Toumei Answer (in which she served as {{The Lost Lenore}} to Shintaro). [[spoiler:And when she was confirmed to be [[BigGood Mekakushi Dan's founder]] and Kido, Seto, and Kano's [[CoolBigSis surrogate older sister]]]], her popularity skyrocketed and she's now arguably the most popular female character, pretty impressive given that she's a {{Posthumous Character}} only seen in flashbacks.
** '''Kuroha''' due to being [[spoiler: EvilIsCool and EvilIsSexy. He's also loved for his general PsychoticSmirk and AxCrazy nature making him a DracoInLeatherPants.]] It helps that he has heavy plot relevance and his song Outer Science is a WHAMEpisode that's catchy.
** Haruka is considered Moe among the fandom. What makes him and Seto popular is their nice guy and Adorkable qualities. [[spoiler: It also helps that he was turned into Kuroha before TheReveal.]]
** Seto's {{Demoted To Extra}} status in the novels, manga, and the PVs practically guarantees him this spot.
** [[TheTrickster Kano]]. He managed to shoot past [[{{Protagonist}} Shintaro]] as the most popular character in the series just after [[ImageSong Yobanashi]] [[EarWorm Deceive]] was released.
* HollywoodPudgy: According to Kido and Shintaro, Momo's quite heavy.
* MemeticMutation: "May soda be eternal".
** [[spoiler: Kuroha]] being associated with bees, in reference to his color scheme.
** "Welcome to my womb".
** Konoha's expressions in the announcement of his voice actor.
** "Maternity Spiral"
* MoodWhiplash: In the Mekakucity Records cd, [[NightmareFuel Outer Science]] plays after [[TearJerker Re:Gunjou Rain]]. And after Outer Science? The upbeat Otsukimi Recital, followed by Lost Time Memory.
** The order in which the music videos were released as well. After Konoha's State of the World, a continuation of Heat Haze Days, Kisaragi Attention was released, which is one of the happiest songs in the series. And following Yuukei Yesterday's release was the [[NightmareFuel Nightmare Fuel-induced]] Outer Science. [[CrowningMomentOfHeartWarming Summertime Record]] was completed two days after.
** Chapters 17 and 18 of the manga. In Chapter 17, we're finishing off Takane's route, it's a little bittersweet, but still optimistic. Then at the very end we see [[spoiler:Kuroha]]. [[spoiler:In Chapter 18, Kuroha immediately brutally murders Seto, Kido, Kano and Ene on page before Mary resets the route.]]
* MoralEventHorizon: Route XX Shintarou arguably crosses it when he [[spoiler: chokes Ene to death when she was just trying to help him.]]
** [[spoiler: Kuroha]], when he [[spoiler:murders everybody.]]
* NightmareFuel: [[spoiler: Kuroha]]'s expression in the [=MekakuCity Records=] crossfade PV.
** Outer Science in general.
*** Everything about [[spoiler:Kuroha]] for that matter.
* OneTrueThreesome: The original Mekakushi Trio, Kido, Kano, and Seto.
** Shintaro, Ene, and Konoha are sometimes shipped as this as well, or for that matter, Shintaro, Ayano, Haruka, and Takane.
* TearJerker: [[spoiler: Ayano's suicide]], and Shintaro's reactions in ''Toumei Answer'' and ''Lost Time Memory''.
** And then ''Ayano no Koufuku Riron'' came along and made it even worse.
** [[spoiler: Challenge. Watch Yuukei Yesterday and then Outer Science. Or just read the manga up to Haruka's death and try NOT to cry a single time. If you win: good for you. If you lose: congratulations and welcome to everyday life of the fandom ]]
** The Kagerou Days time loop, and its affect on Hibiya in Otsukimi Recital.
* ViewerGenderConfusion: Kido. Even Jin was confused with her gender!
* WhamEpisode: ''Lost Time Memory'', with its reveal that [[spoiler: Ayano had an eye power, and Shintaro may have inherited it]].
** ''Ayano no Koufuku Ririon'''s reveal that [[spoiler: Ayano was the sister figure to Kido, Seto, and Kano, and the original creator of the Mekakushi-dan]].
** The [=MekakuCity=] Records booklet, since it reveals that [[spoiler: everyone is actually {{Dead All Along}} who came {{Back From The Dead}} because of their eye powers.]]
** '''''[[FriendlyTarget OUT]][[FamilyUnfriendlyDeath ER]] [[KillEmAll SCI]][[EverybodysDeadDave ENCE.]]'''''
* WhamShot: Towards the middle of the [=MekakuCity=] Records crossfade, the video shows the silhouettes of Takane ([[spoiler:Ene]]) and Haruka ([[spoiler:Konoha]]) as ''Yuukei Yesterday'', their shared song, plays. [[spoiler: It then cuts entirely to Haruka. The video goes dark and he becomes [[FanNickname Kuroha]], as ''Outer Science'' plays]].
* WorldOfWoobie: Pretty much everyone (sans Momo) qualifies as a [[TheWoobie woobie]].
** Momo is actually also a [[TheWoobie woobie]]; it's just that her problems are miniscule compared to everyone else's.