a chicken dies later on in the game.

A chicken does but other than that no.

A chicken dies.

Technically, yes. A chicken is killed and used as a part of one of the murders.

In an optional free time event, a character mentions being bit by a mosquito. Neither the bug nor the bite are shown.

Nope. One character owns a cat, but it's not seen in this game.

Someone poisons herself intentionally

Not in the main story, but one character’s free time events portray a Diet Coke addiction, although this is treated as a joke.

No, but one character does offer to buy the protagonist a 'brewski' in the opening sequence. Due to the closed-circle nature of the situation they're soon shown to be in, this offer cannot be redeemed in-game.

When a killer is discovered and found guilty, they are executed through various methods. The first execution involves someone being beaten to death.

3rd chapter execution. they set it up so it looks like someone is about to be burned alive but instead she is hit by a truck.

no but one of the characters’ eyes appear to be on fire throughout most of chapter 3, though it does not seem to be painful. also probably worth mentioning: one of the characters has a split personality and when they switch, their eyes change (one has round, grey irises, and the other has wavy, red irises)

One of the characters is shown to cut their leg to keep track of how many people they've killed, but the cutting itself never happens onscreen or during the events of the game.

The first execution almost certainly resulted in the character getting some teeth knocked out before their death.

One of the characters is murdered and has their wrist broken during a struggle, though it isn't seen on-screen.

Two characters in chapter 3 die from their heads being smashed with a hammer/mallet. The scenes are bloody, but their heads aren't mutilated.

(Major story spoilers) The first scene of the game is a man being killed in a space ship. Near the end of the game, it is revealed that this man was the father of one of the central characters.

not a toy but one of the characters’ close belongings is repeatedly smashed

Some might argue technically no, but for the sake of trigger warning, yes. (Major story spoilers) Most of the characters are revealed to be approximately 18 years old near the end of the story, but that doesn't mean much when throughout the entire game they themselves and the player believe they're 16 or so years old.

All of the main characters are under the impression that they have been kidnapped.

I mean they're being watched 24/7 via cameras all over the school, I would consider that stalking.

One character believes he has been possessed by his dead classmate's spirit, and he looks and acts differently throughout chapter 3 (original comment by user leofbadger, changed to save spoilers)

There are no ghosts, however there is extensive talk about them (mostly in the context of "this character thinks there is a ghost, we have to explain to them why there isn't")

There is also an Easter egg scene featuring all the girls in the communal bath. It is possible to play through the game without ever seeing the scene if you don't have the right item.

Yes, technically all body discoveries are jumpscares. However, before you find one it always says something along the lines of "There was something waiting for me that I would never forget" then shows the dead body

Multiple character sprites show the characters spitting or drooling

Specifically each time a body is discovered

Not live, but it is mentioned that the protagonist used to wet the bed until he was well into elementary school. This is presented as his most embarrassing secret. While it's far less dire than the secrets of certain others, it might still bring back bad memories.

A certain character "vomits" blood in chapter 4

There's no hospital, but there's a nurse's office in the school that gets visited a lot.

Not necessarily, but if you do Sakura’s free time events she mentions her first love Kenshiro, who has an unnamed terminal illness

Toko is constantly saying how ugly and fat and unattractive she is, despite her being actually very pretty and just as skinny as all the other girls.

Though not an eating disorder, I mention this as it might be triggering: one character grows close to a blackened, and after their execution the character doesn't eat for a few days.

One character poisons herself in the forth chapter and another puts herself through all of the previous executions during the final chapter.

There's the "DID system has a murderer and cr*zy alter" trope, so...... yeah.

It is mentioned that one of the characters cuts her leg (hidden by clothing) every time she commits a certain act. This is not shown.

Certain characters are shown panicking, especially Sayaka.

Technically, yes. The entire game takes place in a school in which they believe they have been trapped in and are being mentally manipulated into killing one another.

The very first scene has someone trapped in an iron maiden-styled rocket before he dies. This may or may not set off claustrophobia.

Yes but camera bobbing while you walk can be disabled in options!!

[SPOILERS] Technically, none of the characters are underaged while having children. They were forced to forget three years of their lives, so while they think they are late teens (around sixteen or seventeen), they are actually closer to early twenties.

There's no explicit nudity or p*********y but there's some sexual remarks and jokes, and an optional scene where the girls are shown in a bath house.

There’s an optional scene where three of the boys, protagonist included, peek into the bathhouse. A female character ends up calling another female character a s**t and another insults a girl on her chest size. One character lies about being sexually harassed.

I don't believe it's discussed in this game, but Leon's cousin Kanon has romantic feelings for him, which he does not reciprocate. Kanon is not featured in this game, but there is an incestuous relationship in a different game in the series (V3).

Not in the game, but one commenter noted that there are in the anime

in her introduction, its mentioned that Sakura is called the "missing link" between humans and apes online. while the game only explicitly connects it to her physical size/strength, she's the darkest-skinned character in the game, so its also pretty racist.

No but he gets a pretty antiblack writing during almost all of his screentime.

there is a character who is an ableist stereotype of people with DID. her alter is extremely murderous, even having "genocide" in her name.

[SPOILERS] No jokes about it, but there is someone who is wearing a skirt that is later discovered to be a man. No ill-treatment though.

One character is overweight, and while it’s not commented on frequently, another character who dies rather early on calls him a fatty a couple times

2 guys who are said to have fallen in love without realizing it" outside of the game both die.

No copaganda present in this game; quite the opposite, actually. The main villain insults one of the main characters for threatening to call the police. In the same scene, he also calls the police "a group of losers".

There's a character who is AMAB, and presented as female to the group. The group discovers they were AMAB after their death, and immediately switch pronouns, without questioning if that's what they wanted to be called.

There is a “bad ending” that could be interpreted as sad, but it’s more humorous considering it’s not really an ending, and after getting it the games takes you back so you can see the real ending

Not a plane, but a space ship does crash early in the game.

Sorta? In the first scene of the game, a man is launched into space. His rocket ship goes up, plummets back down, and opens to reveal that he has become a skeleton during the process.

During an execution late in the game, a fire truck rams into a character, killing them.

Yes. One of the characters, though I won't mention their name (I'm looking at you, other comment), is revealed to have killed their own sibling. There is also another instance in which a character was revealed to have killed their sibling, though it was not intentional.

Almost all of the characters are under 18, and because of the multiple deaths it's safe to mark this as 'yes'

Yes, the game has a lot of blood and gore due to its premise of a killing game. All the blood is bright pink instead of red, which for some people may be enough to not trigger them.

there are guns in the school, though

Not nuclear, but a bomb is set off in one of the later chapters.

Technically...in a way. In chapter 2, of the character's bodies gets tampered with by a certain other character, and it makes it sort of look like a hanging.

There is one character who is grabbed by a chain around their neck. They reach for the chain, either trying to get it off or because they cannot breath.

Well, a fire truck, but yes,