@sickVisionz: NOTE: I have not watched episode 9 yet, but this is my best interpretation of Kasuga's situation.
I don't see how getting away with vandalism and stealing is something to be proud or relieved of. This isn't some American high school movie. Maybe keep in mind that in the manga, the characters are supposed to be in primary school. I don't remember the exact age, but 8-12 maybe.
Kasuga is just trying to come to terms with his identity. On the one hand he wants to be "normal" and fit in with others, but on the other hand he thinks he is both better and worse than the rest of the people in this small town. He thinks he's better because he can read literature and everyone else is fake, but he's worse than everyone because he is basically a criminal who hasn't atoned for his sins. It's the struggle between trying to live up to an idealized image of himself and coming to terms with the sins he has committed.
The problem is that because Kasuga thinks he can't trust anyone with the truth, he continues to internalize his sins and feel bad about it all. The only person Kasuga can effectively trust at this point is Nakamura. Due to Kasuga's isolation he can't succeed to be "normal" with others because he feels that no one will understand him. No one will understand him because, Kasuga thinks, "if no one can understand and read literature like Baudelaire, how can I expect them to understand the truth about who I really am and the sins I committed?"
Okay, now you might be asking, "wait, why doesn't Kasuga just keep it a secret? surely people in real life have done crazy shit and not told anyone, why can't Kasuga do this?" And that's the million dollar question. Kasuga doesn't seem to understand what it means to have "normal" relationships with others. Namely that in order to have a meaningful relationship with another person you don't need to tell them everything and they don't have to understand you completely. Unless Kasuga realizes this, it's all downhill from this point as he continues to dig himself into a hole.
Okay about Saeki supposedly wanting to have sex with him and Nakamura's twisted advances. Again, I think Kasuga is struggling between trying to take the high road and facing his sins and his sexual emotions. For example in an earlier episode Kasuga clearly fantasized about Saeki-san but quickly chastised himself for thinking dirty thoughts saying, "no, Saeki is an angel, Saeki deserves a purer person than I." Clearly Kasuga is imposing some sort of "moral ideal" and he wants to become a better person. BUT since this moral ideal is probably informed by the literature that he reads, Kasuga can't count on anyone understanding it or the struggle that he is going through. Which again results in his further isolation from others, and Kasuga not bothering to build relationships with others. (Except Nakamura, who seems intent on exploiting Kasuga's situation)
About Nakamura, I have never considered her a romantic interest. I have been under the impression that she is only interested in exploiting and manipulating Kasuga. Even if an actual romantic interest has developed between them, it is only because of the sins that Kasuga has committed. Which again, Kasuga would have trouble accepting because of his desire to be a normal person.