Tomoko is autistic.
The series will end with Tomoko starting a manga based on her life.
- The author says that the series is based on her life, so it makes sense.
The finale will be about her and some guy in serious danger of dying,
- So she'll try invoking Must Not Die a Virgin, then will turn out the guy is not a virgin at all, then she confesses her own virginity, awkwardness issues, but she'll get her wish anyway.
- Then she wakes up, turns out it was All Just a Dream or something, but hints are dropped that the life-threatening situation from the dream may happen soon in real-life, cut to black, the end.
Tomoko will never become popular while in high school...
... but she will find happiness, friends and love at some later point in her life. The series will conclude with An Aesop
that having no friends in high school isn't the end of the world, and that life can always get better.
Tomoko is foreign.
- Most likely European or American, given that she has green eyes, but she lives her life in Japan. Japan has a habit of xenophobia (especially since Japan isn't very culturally diverse, 98% of Japan's population is Japanese), and therefore the students could be excluding Tomoko because she's foreign. She grew more and more secluded because of the exclusion. When she started high school, she's had enough of being so introverted and tries her best to fit in, but because she's spent so long by herself, it isn't working.
Tomoko will develop feelings for her brother.
- Tomoko seems to, ever so slowly, be getting closer to her brother. And has in the past thought that him looking at her strangely was an indication that he viewed her as more than just a sister. There will be at least one chapter where she believes herself to be in love with her brother, in that kind of way. Though knowing the manga, it will turn out to be something completely different before the chapter ends. Possibly a momentary lapse in sanity after her brother finally does something kind towards her. She seems to freak out towards anyone showing her even a little bit of kindness after all.
Tomoko is actually Haruhi Suzumiya.
- Because someone had to do this. Tomoko is what Haruhi would be if Haruhi never awakened/received her Reality Warper/GOD status.
Kyubey is stalking Tomoko.
With that much desire within her, she'd make the perfect Magical Girl
- Tomoko is a borderline shut-in, who cannot take normally around anyone except her family. The perfect victim for the NHK's machinations. The boy giving her an umbrella? The middle school kids she hangs around with? All ploys to give her a sense of hope, before it is brutally torn away from her. They'll stop at nothing to turn her into a NEET and a hikkikommori. Nothing, I say!
- Or maybe a mixture of mental issues and internalized misanthropy is keeping her from having friends. Whatever works.
- Because I can't be the only one who is reminded of a really messed up Konata when I see Tomoko.
Episode 12 of the anime...
Each secondary/background character is a protagonist
of their own series.
- Tomoki is clearly more in the life of a sports series (friends, social life, afterschool sports), the students Tomoko sees daily are from a slice-of-life comedy (constantly talking and hanging out), and Imae is the protagonist of her own series; possibly a magical girl (popularity, friendly even to Tomoko). To each of them, Tomoko is a side character of their own series, hence why she never gets a high viewpoint from any of them but Imae who may want her to join her team or just be her friend.
The reason why Tomoki's grown cold toward her sister...
...is because she attempted to molest him in the past. With the things she's interested in and her desire to get laid, she may have tried resorting to rape at one point.
Tomoko has genuine singing talent.
The ending theme has Tomoko sing a tune with an uplifting tone. It tries to go with Stylistic Suck
but frequently slips up, causing Tomoko to sound quite good. She's just a little rough around the edges unless she's starting to have an emotional breakdown, then it goes into the crapper but that's true for everyone. Of course the ending theme is obviously not part of the main story. Chekhov's Gun
? Doesn't quite fit the definition. Foreshadowing
? Yeah, that's more appropriate.
Near the end of the series, Tomoko will get exactly what she wants, and becomes popular.
- ...but later realises her newfound popularity is shallow, and that people don't love her for who she is, so she wishes to return to the honest friendships she had with Yuu and (possibly) Komiyama, the moral of the story being that it doesn't matter being popular as long as there's at least one person out there who considers you a true friend.