Classical Anti-Hero: He is a highly unstable NEET who places all of the blame for his highly unstable life on a conspiracy organization known to him as the NHK. Yet he is ultimately a good-hearted person who wants to be a productive member of society, and most of his angst stems from feeling he is unable to lead a productive life.
Meaningful Name: It's actually in the fact that it doesn't mean much. The surname Satou/Sato is so common in Japan that it is meant to represent the majority of Japanese society and what they struggle with. The English equivalent would be naming the main character Smith.
Broken Bird: She flinches noticeably when she presumes another character is going to strike her because of the fact that she was forced to live with her abusive stepfather who constantly beat her, and she also attempts suicide by throwing herself off the same cliff her mother did years before.
Girl Next Door: Her innocence and rather plain beauty is, at first, an integral part of her relationship with Satou, combining this trope with Manic Pixie Dream Girl. However, both tropes become subverted when she is slowly revealed to exhibit nearly every symptom of a textbook case of Borderline Personality Disorder, including extreme self-esteem issues, self-harm, skewed social perspective, and an unhealthy (suicidally so) obsession with Satou.
Goodbye, Cruel World!: Misaki spends most of the next-to-last episode talking to Satou about suicide notes, and particularly about one famous suicide note where the writer complimented his parents' cooking. She leaves a suicide note of that form on her bed ("The New Year's grated yams were delicious. So to everybody, goodbye."), which is Satou's cue to start looking for her.
Limited Wardrobe: She almost always wears the same sweater and miniskirt, even under freezing conditions.
Manic Pixie Dream Girl: Deconstructed, as she gloms onto the Satou because she needs to have the company of people she considers even more pathetic than herself..
Weakness Turns Her On: A rather brutal example. Misaki selects Sato for her "project" of curing him from being a hikikomori, and the time they spend together eventually leads to there being quite a bit of romantic tension between the pair. It's later revealed that Misaki chose Sato, because she wanted to find someone who was even more "worthless" than she was and prove she could fix them because of her abusive stepfather telling her that she was a useless human being. As a broken recluse, Sato fit the bill.
Broken Bird: She appears to be successful despite her constant ravings about conspiracies. However, in the middle of the series, it is shown she is a bit of an outcast at work and unhappy in her relationship, even to the point that she joins a suicide pact and seems intent on jumping off a cliff over the ocean, until her boyfriend asks her to marry him, thus saving her.