Is it torture porn? Maybe, if you've never lived through some of what Ayumu experiences. Suenobu absolutely nails the "no way out" feeling of being the target of bullies, and if Ayumu has more than her fair share (not that there's any such thing as a "fair share" in this case), it serves to illustrate how difficult it can be to just get someone to notice. Miki comes the closest to being there for Ayumu, but she's got her own problems, and as a fellow child, it's not her place to stand up...though even when the bullying is literally under his nose, their homeroom teacher does exactly nothing. This series hurts.
CW: self-harm, suicide ideation, sexual assault