This is how Fuminori sees the world all the time.
This is what you get if H. P. Lovecraft worked in Visual Novels.
All spoilers below are unmarked. Proceed with caution.
- Honestly, who wants to live with the fucked up senses that Fuminori got after the accident? The very first shot we get is of the fleshy lumps that represent his friends talking with jumbled text◊ and distorted speech to boot. It ain't pretty.
- This game features literal wall to wall guro the majority of the time, a tentacle monster that rather graphically kills and eats people, your protagonist can either go from wistful madman in an asylum (sad ending for him and Saya since they may never see each other again), heartbroken madman on a transformed earth where all humans have changed into tentacle monsters (bittersweet ending for him and Saya since their "children" are taking over the world, sad ending for pretty much everyone else), or killed in a horrifically graphic manner that just gets worse with the "censor filter" off (sad ending for him, Saya and every other major character. Happy ending for anyone who wasn't involved in this fucked-up plot. Noticing a theme?). Oh yeah, it's an H game with a girl who can literally Mind Screw people. She's the tentacle monster.
- Cannibalism, this was coming due to Fuminori's warped senses and to what Saya is but the way it is described is horrifying on Fuminori's POV and who the person that he is eating from.
- Soon after this is the first main crossroads of Saya No Uta. You could have Saya return Fuminori's senses to normal, which leads to him being incarcerated in an asylum (more detail on that in the endings below), or have Fuminori reject his humanity and say that he doesn't mind eating human flesh, making him a Villain Protagonist.
- While eating Oumi, Saya says she hasn't had food this big in a while, and she usually catches them in the nearby park.
- Saya has access to a dog collar. It was mentioned that there were incidents where local dogs and cats have gone missing.
- There's a couple songs from the soundtrack that stand out as Nightmare Fuel material, namely "Scream" and "Scare Shadow", with the distorted guitar making them sound all the more insane. "Scare Shadow" in particular starts out as a relatively "normal" creepy song but progresses to a middle part that's totally different. The start (and the end, which is the same) still obey some laws of sound itself, the middle part just... does not.
- Don't forget that loud, distorted noise appearing half way in both "Saya's Song" I and II, but also at the end of "Sin", and even in the vocal version of "Saya's Song" which may or may not be Saya's true voice.
- "Saya's Song", which is unnervingly eerie deep beneath its astoundingly beautiful tongue - an ugly monster in the guise of a beauty, which is what Saya is.
- Picture this scenario: You are a family man that has a daughter, a great marriage, and all is well. Soon after, your neighbor start giving you a new way to "see" things and as a result you immediately Go Mad from the Revelation and killed your wife and daughter. You also lose all sense of reason so when you "see" that neighbor, you rape her (which itself stands out as NF). Yeah, Yousuke had it rough.
- Dear God, the rape scene. Seeing the mind-corrupted Yousuke deriving pleasure from Saya's helplessness as he rapes her was too much.
- Yoh's fate. Mutated into... whatever Saya is, just so she can serve as a family pet-turned-mindless sex slave, just aware enough of herself to really wish she'd been killed instead. (In fact, Fumninori explicitly acknowledges that what Saya has done is horrible and sadistic, and that the merciful course of action would be to just kill Yoh. He goes ahead and rapes Yoh anyway because he finds Saya's jealousy-driven behavior very human-like and endearing.) She is so broken by the time she escapes and meets Kouji that she gets Mercy Killed by him and when Kouji meets Yoh at that time, she doesn't resemble anything human.
- Koji's almost-fate in the well. Picture it - you're hours away from any semblance of civilization, and someone you thought to be your best friend tricks you and leaves you to die of exposure, hypothermia, starvation, or dehydration. And no matter how hard you scream or shout, no one will hear you and you will die alone. Luckily for him, Ryoko had enough foresight to predict Fuminori might try to do something.
- The endings. No matter which ending you got someone WILL face a tragic fate and Fuminori and Saya will never get to be together. It IS an Utsuge after all. Those people are:
- Fuminori in ending 1, where he's locked away in a sanitarium, probably for the rest of his life, and will likely never see Saya again as the two say goodbye forever using text messages on a cell phone passed back and forth underneath his cell door. This ending is achieved if you accept Saya's offer to restore your senses. Ironically enough, this ending has the LEAST amount of death and suffering in comparison the other two below yet this one is seen by some as a Non-Standard Game Over. This isn't the best ending for humanity as a whole though.
- Dr. Tanbo in ending 2, where Saya "blooms" and every human in the planet changes into her type of life form, but Dr. Tanbo, being high up in the mountains where the spores have trouble reaching, transforms agonizingly slowly over the course of weeks as she completes transcribing Dr. Ougai's research on Saya for her own personal pride. At one point she even chops off one of her arms that had undergone the transformation while the rest of her was still human. As she finishes reading Ougai's notes, we also get a brief glimpse at the city, where giant splotches of flesh litter stairs and buildings, all while we don't get to see any other humans (if there's even any left... we don't even get to see what Tanbo looks like now. This ending is achieved if in the Final Battle Dr. Tanbo didn't appear and Fuminori and Saya killed Kouji.
- And finally, Kouji in ending 3, as the only survivor of the Final Battle and last person remaining with knowledge of the now-deceased Saya's true nature and Things Man Was Not Meant to Know has to live knowing he can't talk with anyone about what he's witnessed lest they think he's crazy (which he partially is at this point and likely getting worse), his girlfriend and two best friends dead, and a revolver loaded with one bullet hidden in his bathroom in case the day ever comes he can't take his schizophrenia and hallucinations anymore and commits suicide. In this ending, Dr. Tanbo appears to help Kouji, they both successfully killed Saya, Fuminori kills Dr. Tanbo, and seeing that Saya is dead, Fuminori commits suicide. Yet with all that death, this is also the best ending for humanity in general.
- Fuminori dies in a particularly gory way in this ending, by repeatedly smashing his face into the blade of an ax. Thankfully, we don't get to see it.