Deconstruction: Very much so, of the typical Ecchi "protagonist is a pervert but that's ok" genre. The hero is a pervert, but it's considered a horrible thing, he grows out of it and his life vastly improves because of it, he takes the blame for what he did voluntarily and everyone has a realistic reaction, the tortured girl snaps realistically after years of bullying, including several off-screen suicide attempts, being a Hikikomori is considered a very bad thing, etc., etc.
Although Kurosawa is still a pervert even after the heart change and facing most of the consequences for his actions, he still masturbates and fantasies about schoolmates in college High School (just privately). But he stopped being a antisocial, misogynistic and egoistical reject.
Yes, the problem was much moreso the fact that Kurosawa was very cynical loser and thought very little of everyone else, which is pretty much why any female he knew wouldn't be anything more than a sex object to him, if they were attractive. The whole point of the story is about him realizing that he's wrong, that people are good and having relationships with them is worth it; masturbation was just a metaphor for antisocial behavior in general.
Genre Shift: Starts off as a Death Note parody/ecchi crossover with lots of fapping with a slight dark edge in regards to the bullying but a hint of fluffy romance... and then the fluffy romance turns into a crushing love triangle, the main character getting worse and worse until he realises what he's done and fully admits his crimes causing his rather horrifying and realistic atonement, the first bullying causes the victim to snap and become a suicidal recluse. But they all get better.
Heel Realization: Kurosawa, upon seeing Takigawa's painting. He confesses to his actions soon after.
Hikikomori: Kitahara becomes one after she snaps. It's not played for laughs nor is it handwaved — it's mentioned that her mother has had to stop her from committing suicide multiple times, and she's openly terrified for her daughter's safety when Kurosawa comes to visit.
Hurricane of Puns: Perhaps the oddest example in fiction. It really isn't one in the original language, but when you translate it into English, it becomes a "Coming" of age story about the "Master of Masturbation."
Important Hair Cut: A couple of them - Takigawa before she entered middle school, and Kitahara at the very end of the series. You can also tell that Takigawa really is dating Nagaoka when you see her come to school essentially cosplayingTsuruya.
Sliding Scale of Idealism Versus Cynicism: As it starts out as a Death Note parody, it begins pretty far on the cynical end of the scale, starting of with a showcase of humanity at its most dickish, misanthropic, and cruel. It ends far, far on the other end of the scale, with an unflinchingly optimistic message about taking the high road, friendship, inner strength, and forgiveness, with even Kitahara, after all the hell she goes through and inflicts, making it through her shut-in phase with Kurosawa's support.
The series' title, specifically the word "onani" due to different modifications to Hepburn Romanization and the debated status of the proper romanization of elongated vowels sounds. The dropping of the long vowel is the most common interpretation amongst the fanbase.
Takigawa has her last name constantly misspelled as "Takagawa".
Third Option Love Interest: So does Kurosawa end up with Takigawa, who he had a crush on, or Kitahara, the one he eventually defrosts? Neither of them. He actually ends up with Sugawa, the bully and his first victim, since by the time they start getting together, she has become much less mean and more Tsundere.
Wham Episode: When Takigawa and Nagaoka are revealed to be dating. The cries and shouts of unsuspecting new readers can still be heard in various sites to this day. The series just takes a completely different turn from that point on.