A troper pointed out on the character page how Kido's physical abuse on Kano crosses the line when you think about Kano's past (and this itself is a Fridge Horror). Well, I felt it would be sort of OOC for Kido to do something so insensitive like that while knowing this fact about Kano. While speculative, maybe Kido doesn't really know that much of Kano's past. This isn't unbelievable considering this is Kano and that he seems to not want to blame his mother for what happened, hence his wish for the eye power. Maybe he hasn't exactly gotten over that and some how tries to keep his mother alive by invoking this reaction from Kido.
In the latest novel, we learn that pain shuts off Kano's ability. It's possible that either A; Kido purposely hits him a lot to make sure he doesn't over use his eye power, or B; Kano purposely provokes her into hitting him as a way of policing himself.
A seems to be true for some cases in the latest novel since Kido does catch Kano once with a fake smile and hits him, telling "Ill do that more often if I feel something is off"
Yet another layer of Fridge Horror comes up when you realize that Kano associates himself with the concept of pain, which is why pain shuts off his power. What kind of self image does someone have to have that physical pain becomes an intrinsic part of their identity.
What do Haruka and Takane's families think happened to their children? Obviously they never got to give them proper funerals, as Haruka became Konoha, and Takane's body has been kept in a hospital for two years. Do they consider them missing people?
This also goes for everyone who was pulled into the haze and didn't come out (Hiyori, Ayaka, Shion, ect.)The only one not considered 'missing' is Ayano, only because Kano was forced into pretending to be her corpse while Kenjirou spread it around that she died of suicide.
The fifth novel and episode 11 and 10 of the cartoons state that Kenirou's snake has several resources from the police, hospitals, etc. It was able to get away with the disappearances Haruka and Takane without causing questioning. Also, Ayano's death is faked by Kano by an order of the snake
Mary is 140 years old, ageing one year for every ten. She said she had counted 100 summers since her mother disappeared. Mary had been living on her own in the woods since she was the medusa equivalent of a four year old.
A small one spawned by the cartoons's last episode; Konoha's ideal body was destroyed in the process of bringing Hiyori back to life, however, Haruka is also alive again. Does this mean he still has to deal with his illness? If so... how long until the ticking time-bomb goes off again?
A rather heartbreaking one occurs when you remember the snakes are what was keeping everyone who had one alive. When the wide eyed snake Leaves Kenjirou's body, he dies with no way to be brought back, leaving the trio, and now Ayano, orphans once again.
Consider this; Mary ages a tenth of the rate of a normal human, and she is shown to be incredibly unstable when it seems she is going to lose her friends - to the point of forcibly hitting the Reset Button. So... what happens when everyone else dies by the time she is in her 20s (in Medusa years)?
The Days PV serves as one for Mekakucity Actors. In it, Azami, Tsukihiko, and Shion take a train to somewhere, with Azami's train passing by the train from the anime's ED. Azami wanted her family to live together in an endless world, and thus they are taking the inbound train into the Daze. Hiyori's train, in that case, is taking the outbound route, reflecting the ending of the series where she and the rest of the Gang managed to survive the events of the story.
Why was Shintaro complaining about the hot summer weather when he could have just taken his jacket off? At the end, it's obvious why he wouldn't want to take it off. Red is the color of the hero.
In the videogame Hatsune Miku: Project DIVA 2nd, the song Kagerou Daze is playable. This song can also be translated as Heat-Haze Daze. One module usable by Kagamine Rin in this game is "Heat Haze". The main colors of the module? Black and red.