These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
So has Hiro-chan - on this very wiki, even. Was her attempt to kill Shunji a cruel method of trying to get Shiina to join her cause, or was it simply her way of forcing Shiina to kill her? And when she says "let's be friends" in the same scene, did that mean she never truly thought of Shiina as a friend in the first place, or did she just mean she wanted Shiina to still be her friend even while she's messing up the world to suit herself?
What could be the justification for the Sudo gang? Are Bungo and Satomi doing what they believe is right? There are dozens of fan-generated ideals. Sometimes goes into Ron the Death Eater territory.
Complete Monster: The minor villains tend to be very much like this. They include Aki Honda and her posse (except for Miyoko), who force Hiro-chan to ingest worms from a beaker, then go on to rape her with a test tube, and the city thugs that needlessly and brutally rape and torture Norio to death - right down to calling in another thug to do the raping - before cutting his head off and mounting it onto his favourite doll for Takeo to come home to late in the manga.
The Woobie: Akira, most prominently. Given all the crap she goes through, it's hard to not feel at least a bit sorry for her. Many other characters could qualify as well, though they tend to be either Jerkass Woobies or Woobie, Destroyer of Worlds.