There are multiple instances of extreme gore, but one I can site is in chapter seven, when a character gets hit by a car. As well as later in the chapter a corpse rising from a coffin decaying
A side character is jealous of the main couple's relationship and tries to get the boy to leave his girlfriend for herself. But the character was never a true threat to their relationship.
A character who shaves her head in a mental breakdown winds up hospitalized, and this may visually trigger someone because she resembles a cancer patient. However she has no disease.
At one point, a monster is jumping after the protagonist and constantly losing guts and parts of its body. Blood is often, as well as death by morbid unusual causes.