Komeiji Koishi no Dokidoki Daibouken

Komeiji Koishi no Dokidoki Daibouken is a series of Touhou Fan Vids from Nico Nico Douga by Sentakubune. It is well-known in Japanese Touhou fandom for its Crap Saccharine World depiction of Genskoyou where everyone is Driven to Madness.

Can be seen here.

Tropes used in Komeiji Koishi no Dokidoki Daibouken include:

Alien Invasion: Youkai Invasion lead by Youkai Hitler Byakuren.
Anyone Can Die
Appendage Assimilation: Head Assimilation.
Art Evolution
Ax Crazy: Pretty much everyone, including Koishi.
Beware the Nice Ones: All over the place, best exemplified by Sanae.
Big Bad Ensemble: Koakuma seems to apparently be this along with Byakuren Hijiri, but the two don't seem to know about each other.
Big Damn Heroes: Marisa and Alice performs a short one when they saved Nitori from being burned to death by a very evil Hina. Kanako also performed this awesomely for Sanae who was being bullied..
Bloodier and Gorier
Blood-Splattered Innocents
Break the Cutie
Cold-Blooded Torture
Crap Saccharine World
Creepy Child: Koishi and Flandre.
Curb Stomp Battle: Reisen incapacitates Reisen
Dark Messiah: Byakuren
Dead Ex Machina: After apparently being killed off by Tewi (Having her legs smashed from her body), Udongein does this and saves Reimu's head from being blown by Reisen II's moon rifle by using Instant Sedation on Reisen II.
Death Equals Redemption: Sanae remembers in her dying moments why she came to Gensokyo in the first place and realizes what kind of monster she had become.
Driven to Madness
Dying as Yourself: Sanae.
Dysfunction Junction: The Scarlet Devil Mansion seems to be one.
Face Heel Turn: Many do this at the beginning or they were Evil All Along.
Fan Vid
Fingore: When Koishi Gets locked up in a room, she tries to claw at the door until all her nails are BARELY attached to her fingers. Then when the story comes back to her again, we find that all her nails have fallen off. Squicky indeed.
For Want of a Nail: If only they just gave Koishi the fishing rod that she wanted....
Freudian Excuses: All over the place.
Gambit Pileup: Starting to look a little something like this.
A God Am I: Koakuma and Byakuren.
Gorn: Lets just say things can get pretty graphic....
I Am a Humanitarian: Yuyuko is a Humanitarian and a Ghostitarian. Poor Youmu....
In-Joke: The "fishing rod" is becoming this with people with knowledge of the series advising others to "carry a fishing rod" just in case.
Late Arrival Spoiler: There has been many fanarts depicting the most important twists of the story including Koakuma turning out to be the Big Bad, Koishi's supposed death and her double resurrection fusion with Yukari who also supposedly died, and Reisen Udongein's seemingly Dead Ex Machina
Mad Love: Koakuma towards Patchouli.
Mercy Kill: A tired and emotionally distressed Satori does this to Orin
Oh Crap: A Villainous example, Hina has this moment when she notices one of Alice's explosive dolls about to explode..
Poor Communication Kills: Remilia, toward Flan. Remilia was not there to save Meiling or Flan from Koishi's rampage, because she was at Reimu's discussing Flan's improvement and showing the parasol she had planned to give Flan when she returned to the mansion. As a result, Flan believes Remi only sees her as a burden, which is why she wasn't saved.

Patchouli: You really don't know how to talk to her, do you?

Random Events Plot
Roaring Rampage of Revenge: Sanae's Bullies react to their humiliation by Kanako's hands by burning her house down, with her parents inside. Sanae keeps the chain going by slaughtering them to the one.
- Also, Reisen II implies that this is the motivation behind the Hate Plague-like events up to now.
Soundtrack Dissonance: To some very successfully disturbing effects. For example, Byakuren announces she's pretty much Youkai Hitler to Everybody Was Kung Fu Fighting. The direction helps, too. The way the whole scene is shot makes her come off as some kind of genocidal televangelist.
Shout-Out: Episode 9's head assimilation scene with Koishi's body fusing with Yukari's head is a possible reference to Jojo's Bizarre Adventure at the end of Part 1: Phantom Blood where Dio attempts to assimilate Jonathan Joestar's body as his own. And just like Dio, it is successful.
Sharing a Body: Koishi and Yukari with Koishi being the dominant personality.
Tragic Villain: Possibly many of the villains, including Koakuma.
Unwitting Pawn: Strangely enough, the deeper the series goes, the more it seems Koishi herself is one of these.
Why Am I Ticking?: A strange and horrifying variation: 1) They're fuse lit bombs. 2) They're sown into the stomachs of the victims. 3) The living bombs are fully aware of it.
Widget Series: Which is another reason other than the above to nickname this series as Koko's Bizarre Adventure.
Woobie, Destroyer of Worlds: Sanae.