One of the character's father is shown to verbally abuse his wife. The act of punching walls and throwing things from both parties as a result of this is mentioned.
There's a mention of an infested toy poodle corpse being found within a locker when interacting with said locker, though it is not described graphically.
All the major character in the game are children, and basically all of them can die in the game, most are avoidable, but two of them will die no matter what (assuming you're going for the true ending)
One avoidable death scene, and one unavoidable death scene, are both suicides. Also, one character seemingly dies from suicide, but it's later revealed to actually have been a murder. One character considers suicide in one ending, but is stopped before they can go through with it.
One of the game's main themes is that mental illnesses, such as depression, are not recognized as "real" by society (people suffering from it are instead treated as "just lazy"), and to show the negative consequences of this mindset. As such, many characters act dismissive and disrespectful towards mental illnesses.
There are several rather gory death scenes, most of them are avoidable, but some aren't. Most of the gore is in pixel sprite form but is still rather graphic, and there is one CG image featuring a decapitated head.